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UNIVERSITY OF CALIFORNIA 
LOS ANGELES 





AGRICULTURAL PUBLICATIONS 
C. V. PIPER, CONSULTING EDITOR 



LABORATORY MANUAL 

OF 
FRUIT AND VEGETABLE PRODUCTS 




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LABORATORY MANUAL 

OF 

FRUIT AND VEGETABLE 
PRODUCTS 



AGRICULTURAL 
BY UBRARV 

UCR 



W. V. CRUESS, B. S. 

ASSOCIATE PROFESSOR OF FRUIT PRODUCTS 
UNIVERSITY OF CALIFORNIA COLLEGE OF AGRICULTURE 

AND 
A. W. CHRISTIE, M. S. 

ASSISTANT PROFESSOR OF FRUIT PRODUCTS 
UNIVERSITY OF CALIFORNIA COLLEGE OF AGRICULTURE 



AGRICULTURAL LIBRARY 



FIRST EDITION 



McGRAW-HILL BOOK COMPANY, INC. 
NEW YORK: 370 SEVENTH AVENUE 

LONDON: 6 & 8 BOUVERIE ST., E. C. 4 

1922 



COPYRIGHT, 1922, BY THE 
McGRAW-HiLL BOOK COMPANY, INC. 

AGRIC. DEfT. 



Agric. Dept, 



PREFACE 

Although food preservation has been definitely correlated with the 
development of modern civilization, it has been one of the last of the 
arts to attract the attention of scientific men. It is only within the past 
thirty years that the principles and practices of food preservation have 
received the intelligent investigation which they merit. Although there 
are yet many problems demanding solution, much has been accomplished 
toward an exact understanding of the scientific principles underlying the 
manufacture of food products. 

The preparation and preservation of fruit and vegetable products have 
become of great economic importance, but this subject has not received 
the attention it deserves in the curricula of educational institutions. In 
many horticultural industries, manufacturing and marketing have become 
of as great importance as production. There is a rapidly growing demand 
for persons trained in the scientific principles underlying these industries. 
Practical knowledge alone no longer suffices. 

This manual meets the need for a reliable guide in laboratory courses 
in colleges of agriculture, schools of domestic science, etc., in the manu- 
facture, preservation and examination of fruit and vegetable products. 
It is the outgrowth of a course given at the University of California 
during the past eleven years. 

The Assignments are designed to simulate as closely as is possible on 
a small scale present commercial practices as well as to illustrate the 
fundamental scientific principles involved. Although this manual should 
be supplemented by lectures or books giving correlated information, much 
valuable data are included, especially in tabular form. 

Although intended primarily for use in Agricultural Colleges and 
Domestic Science schools, much of the information given is of value to 
growers, manufacturers of fruit and vegetable products, food inspectors 
and chemists, home demonstration agents and girls' club leaders, and 
teachers of Agriculture and of Domestic Science in secondary schools. 

WILLIAM V. CRUESS. 

ARTHUR W. CHRISTIE. 
BERKELEY, CAL. 

> 1922 




CONTENTS 



PAGE 
v 



PREFACE 

ASSIGNMENT 

I. Determination of the Grade of Commercial!} 7 Canned Fruits ... 1 

II. Examination of Sound and Spoiled Canned Fruits and Vegetables . . 5 

III. Experimental Canning of Fruit 9 

IV. Practice in Fruit Canning 15 

V. Determination of the Grade of Commercially Canned Vegetables . . 17 

VI. Experimental Canning of Vegetables 20 

VII. Practice in Vegetable Canning 22 

VIII. Examination of Tomato Products 25 

IX. Experimental Preparation of Tomato Puree 31 

X. Practice in the Preparation of Tomato Products 32 

XI. Examination of Commercial Fruit Juices 35 

XII. Experimental Preparation of Fruit Juices 37 

XIII. Practice in the Preparation of Fruit Juices 40 

XIV. Preparation of Fruit Syrups 43 

XV. Examination of Commercial Jellies, Jams, Marmalades and Preserves . 46 

XVI. Experimental Preparation of Jelly and Marmalade 48 

XVII. Practice in the Preparation of Jelly and Marmalade 51 

XVIII. Experimental Preparation of Pectin and Jelly Stock 55 

XIX. Practice in the Preparation of Jam, Butter and Paste 57 

XX. Experimental Preparation of Fruit Preserves 59 

XXI. Practice in the Preparation of Fruit Preserves 60 

XXII. Practice in the Preparation of Candied Fruits 62 

XXIII. Examination of Commercially Dried Fruits and Vegetables .... 64 

XXIV. Experimental Drying of Fruits and Vegetables 68 

XXV. Practice in Fruit and Vegetable Drying 72 

XXVI. Practice in the Preparation and Refining of Fixed Oils 75 

XXVII. Practice in the Preparation of Essential Oils 77 

XXVIII. Examination of Commercial Vinegars 80 

XXIX. Experimental Preparation of Cider Vinegar 82 

XXX. Practice in the Preparation of Fruit Vinegars 84 

XXXI. Practice in the Preparation of Sauerkraut and Pickles 86 

XXXII. Practice in the Preparation of Fruit Acids 89 

XXXIII. Practice in Olive Pickling 92 

XXXIV. Practice in the Preparation of Museum Specimens 95 

METHODS OF ANALYSIS 97 

SELECTED REFERENCES 107 

INDEX . , Ill 



vn 



LABORATORY MANUAL 

OF 

FRUIT AND VEGETABLE PRODUCTS 

ASSIGNMENT I. DETERMINATION OF THE GRADE OF 
COMMERCIALLY CANNED FRUITS 

Materials. Cans of each of the different grades of the more impor- 
tant canned fruits, such as cling-stone peaches, free-stone peaches, 
apricots, pears, cherries, strawberries, blackberries, and olives. 

Procedure : 

1. Weigh the can. 

2. Cut the can and empty the contents on a piece of Vs-inch mesh 
screen and drain for at least two minutes. Weigh the drained fruit and 
measure the volume of syrup. Weigh the empty can. Compare the 
drained weights with those given in the Appendix, Table XV. 

3. Count the number of pieces of all fruits except berries. 

4. Determine the Balling degree and temperature of the syrup. By 
use of Table XIII in the Appendix make the necessary temperature 
correction. Determine the Baume degree of the brine from the olives. 

5. Determine the acidity of the syrup as directed in Methods of 
Analysis, page 98. Apples and pears contain malic acid, grapes tartaric 
acid, and other fruits citric acid. Determine the reaction of the brine 
from the olives. 

6. Carefully note and compare the appearance and flavor of the 
fruit and syrup for the different grades. 

7. Note the appearance of the interior of the can; i. e., whether it 
shows evidence of excessive corrosion or the accumulation of iron or tin 
oxide. 

8. Determine the grade of each sample by reference to the Specifica- 
tions for Canned Fruits and Tables I and II. 

9. Ascertain the probable concentration of syrup added at the time 
of canning to the different grades of fruit examined. 

l 



Suggestions: ' 

SPECIFICATIONS FOR CALIFORNIA CANNED FRUITS 
(Adopted by the Canners 7 League of California) 

General Description of Grades: 

Fancy grade or superlative quality consists of fruit of very fine color, 
ripe yet retaining its form, not mushy, free from blemishes, with the 
pieces uniform in size and very symmetrical. 




FIG. 1. Balling hydrometer, cylinder and thermometer. 

Choice grade or fine quality consists of fruit of fine color, ripe yet 
retaining its form, not mushy, free from blemishes, with the pieces 
uniform in size and symmetrical. 

Standard grade or good quality consists of fruit of reasonably good 
color, ripe yet not mushy, reasonably free from blemishes, with the 
pieces reasonably uniform in size and reasonably symmetrical. 



Second grade or second quality consists of fruit tolerably free from 
blemishes, pieces tolerably uniform in size, color and ripeness. 

Pie grade or pie quality consists of wholesome fruit unsuited for the 
above grades. 

Table I gives the number of pieces per No. 2 1 / can for the five grades 
of each fruit and also the percentage of sugar in the syrup placed in the 
can. 



TABLE I. CONCENTRATION OF SYRUP AND NUMBER OF PIECES PER No. 2^ CAN FOR 
CALIFORNIA CANNED FRUITS 





Apricots (Halves) 


Pears (Halves) 


Peaches (Halves) 


Grade 


Pieces per 
No. 2J^ can 


Per cent 
sugar in 
syrup used 


Pieces per 
No. 2^2 can 


Per cent 
sugar in 
syrup used 


Pieces per 
No. 2^i can 


Per cent 
sugar in 
syrup used 


Fancy . . . 


24 or less 


55 


6 to 12 


40 


6 to 12 


55 


Choice . . . 


30 or less 


40 


6 to 15 


30 


6 to 15 


40 


Standard. 


42 or less 


25 


6 to 21 


20 


6 to 12 


25 


Second. . 


No limit 


10 


No limit 


10 


No limit 


10 


Pie 


No limit 





No limit 





No limit 


o 


















Cherries (Black or White) 


Cherries (Royal Anne) 


Grapes 


Plums 


Grade 










Per cent 


Per cent 






Per cent 




Per cent 








Pieces per 
No. 2]4 can 


sugar in 
syrup used 


Pieces per 
No. 2^2 can 


sugar in 
syrup used 


sugar in 
syrup when 
canned 


sugar in 
syrup when 
canned 


Fancy . . . 


Not over 100 


40 


Not over 85 


40 


40 


55 


Choice . . . 


Not over 125 


30 


Not over 105 


30 


30 


40 


Standard 


Not over 175 


20 


Not over 145 


20 


20 


25 


Second . . 


No limit 


10 


No limit 


10 


10 


10 


Pie 


No limit 





No limit 














Canned Fruit Salad: 

Count: Contents divisible into portions approximately uniform as 
to variety. 

Syrup: Not less than 40 per cent, sugar. 

Description: Color of fruit to be good for each variety; ripe, yet 
not mushy, and free from blemishes serious for the grade; pieces 
of each variety of fruit to be uniform in size and symmetrical. 



LABORATORY MANUAL 



Table II gives the relation between the grade of the fruit and the 
Balling degree of the syrup after canning. This is known among canners 
as the "cut out" test of the syrup. 

TABLE II. APPROXIMATE CONCENTRATION OF SYRTJP FROM VARIOUS GRADES OF 
CANNED FRUIT "CuT OUT TEST" 

(Compiled from U. S. Dept. Agr. Bull. 196 by A. W. Bitting) 





Fancy 


Choice 


Standard 


Second 


Pie 


Fruit 


Grade 


Grade 


Grade 


Grade 


Grade 




Balling 


Balling 


Balling 


Balling 


Balling 




Degree 


Degree 


Degree 


Degree 


Degree 


Apricots (Royal) 


34 


27 


20 


14 


9 


Cherries (Black Tartarian). 


28 


23 


18 


14 


10 


Cherries (Royal Anne) .... 


26 


22 


18 


15 


10 


Grapes (Muscat) 


28 


24 


21 


17 


12 


Peaches 


31 


22 


17 


11 


9 


Pears (Bartlett) . 


25 


21 


16 


14 


11 


Plums (Green Gage'' 


34 


27 


19 


13 


9 















TABLE III. COMMERCIAL SIZE GRADES OF CALIFORNIA RIPE OLIVES 



Grade No. per Pound 

Small 120 to 135 

Medium 105 to 120 

Large 90 to 105 

Extra Large 75 to 90 



Grade No. per Pound 

Mammoth 65 to 75 

Giant 55 to 65 

Jumbo 45 to 55 

Colossal . ..35 to 45 



Ripe olives of the best quality should have a uniformly black or dark 
brown skin. The flesh should be tender, but not soft, light in color, and 
should not adhere tightly to the pit. 



ASSIGNMENT II. EXAMINATION OF SOUND AND 

SPOILED CANNED FRUITS AND 

VEGETABLES 

Materials. One can each of the best and poorest grades of several 
varieties of canned fruits and vegetables, including tomatoes. 

Several spoiled cans of fruits and vegetables. Samples of "flippers," 
"springers," "swells," "leakers," and "flat sours." 

Procedure : 

1. Examination of Sound Samples. Determine the vacuum within 
the can by piercing the top with a vacuum can tester. Open the sound 
cans of fruits and vegetables and compare the different grades as to 
appearance, flavor and odor. 

Place a drop of syrup or brine from each sample on a microscope 
slide and cover with a cover glass. Examine carefully under the high 
power of the microscope (500 or 1,000 diameters magnification) and 
compare the numbers of organisms found in the liquids from the best 
and poorest grades of each product. In similar manner mount, examine 
and compare samples of the pulp. 

2. Examination of Spoiled Samples. Compare external appearance 
and internal pressure of a "flipper," a "springer" and a "swell." 

Open the spoiled samples and compare the appearance of each with 
that of sound samples. Note the odor. Do not taste spoiled canned food, 
because it may contain Bacillus botulinus and be poisonous. 

Examine the syrup or brine from each sample under the high power 
of the microscope. Make sketches of the organisms found. Carefully 
compare the microscopical appearance of the organisms found in the 
spoiled canned fruits with that of the micro-organisms from the spoiled 
canned vegetables. 

3. Examination of the can: 

A. By Pumping. Cut a circular opening in one end of the unopened 
can of such size that it can be closed later by soldering on a cap. Re- 
move the contents of the can and rinse thoroughly. Boil the can in water 
about one hour and again rinse and drain. Cans with rubber gaskets 
should be dried about one hour at 175F. Paper gasket cans need not 
be dried. Solder a cap over the opening and through a small hole in this 
cap admit compressed air. At intervals of 5 pounds pressure submerge 
the can in water and observe carefully for escaping bubbles. The maxi- 

5 



6 LABORATORY MANUAL OF 

mum pressure to which cans may be subjected without "buckling" de- 
pends on the size of the can. Number 10 cans may "buckle" at 10 to 15 
pounds, No. 3 cans at 15 to 20 pounds, and No. 2 cans at 30 pounds. 
Buckling distorts the seams and causes leaks which did not previously 
exist. The location of leaks should be marked and the can examined to 




FIG. 2. Determining vacuum in a can. 

ascertain the nature and cause of the leaks. (A special apparatus for 
"pumping" cans is manufactured by the American Can Company.) 

B. By Filing. File a cross section through the crimped edge of the 
can a short distance from and on each side of the side seam of the can, 
using a three-cornered file. File through the outer sheet of tin-plate 
between the two cross-section cuts and then press the end "hook" out of 
the seam. This will reveal the condition of the gasket and seam and 



FRUIT AND VEGETABLE PRODUCTS 7 

indicate if the seam was properly made. Both the "factory" end and 
the "cannery" end of a can may be examined to locate faulty double 
seaming. Any seam in the can which showed a leak when tested in A 
above should be examined carefully by filing or in the case of soldered 
seams by separating the tin plate sheets and noting the continuity of the 
solder used in sealing. 

Suggestions : 

1. Definitions. A "swell" is a can which has undergone gaseous de- 
composition by micro-organisms which first releases the vacuum and 
then causes pressure in the can. 

A "springer" is a can the ends of which are more or less bulged, owing 
to the pressure of hydrogen gas generated by chemical action of the 
acid on the contents of the metal of the container, or because the can has 
been overfilled or insufficiently exhausted. 

A "flipper" is a springer of such mild character that the head of the 
can may be drawn in by striking the end of the can on a hard surface. 

The term "flat sour" may be used to cover many abnormalities in 
canned foods, but generally to designate a can of food which has under- 
gone bacterial decomposition with increase of acidity but without gas 
formation. Canned corn occasionally becomes "flat sour." 

A "leaker" is a can from which part of the syrup or brine has exuded. 
Leaks may be caused by external injury, by internal pressure, by cor- 
rosion or by faulty sealing. The contents of a "leaker" may or may not 
be spoiled. 

2. Centrifuging. In order to concentrate the micro-organisms in the 
syrup or brine from sound samples, a small portion of the liquid may be 
placed in a centrifuge tube and subjected to centrifugal action for a few 
minutes. The sediment will contain most of the micro-organisms. 

3. Staining. Yeasts and molds may be examined very satisfactorily 
without staining. Bacteria may be seen more clearly under the micro- 
scope if stained. Place a drop of the liquid on a glass slide. Dry it, 
without scorching, above a small gas flame. Fix the material by passing 
the slide quickly through the flame several times. Cover with a drop of 
carbol fuchsin. Heat above flame until steam is given off. Rinse in 
running water. Dry above a flame. Examine without the use of a 
cover glass. 

4. Spoilage of canned fruit is usually caused by yeasts which enter 
the can through leaks after sterilizing and is rarely due to insufficient 
sterilization. The spoilage of canned vegetables, however, is usually 
caused by spore-bearing bacteria which survive the temperature of 
processing. 



8 LABORATORY MANUAL 

5. The pie grade of most fruits will normally contain a few yeast 
cells and an occasional mold filament. The poorer grades of canned 
tomatoes may exhibit a considerable number of mold filaments and bac- 
teria. The presence of a large number of mold filaments indicates the 
use of decayed material. Large numbers of yeasts or bacteria in sterile 
cans of food indicate that swelled cans or "flat sours" have been re- 
processed. 



ASSIGNMENT III. EXPERIMENTAL CANNING OF FRUIT 

Materials. About 25 pounds of firm ripe canning peaches, 5 pounds 
of firm tart apples, and 5 pounds of firm ripe berries. 

Procedure: 

1. Comparison of Methods of Peeling Peaches. A. Peel and pit by 
hand enough firm, ripe peaches of yellow flesh to fill one can. 

B. Halve and pit a similar quantity and place on a screen tray or in 
a wire basket in live steam for 3 to 4 minutes. Skins of ripe free-stone 
canning varieties can then be slipped from the fruit. 

C. Prepare in an agate-ware pot a lye solution containing 5 grams 
of sodium hydroxide per 100 c.c. of water. Heat to boiling. Immerse 
single halves of the unpeeled fruit in the boiling lye 10, 20 and 30 
seconds respectively and rinse thoroughly in running water. This will 
determine the length of immersion required for peeling. Peel enough 
fruit by this method to fill one can. Remove all trace of lye from the 
fruit by thorough rinsing. Record the loss in peeling by the three 
methods. Fill the cans of peeled fruit with syrup of 30 Balling. Ex- 
haust 5 minutes in live steam; seal and sterilize 20 minutes at 212F. 
After 48 hours or longer examine the fruit and syrup carefully for flavor 
and appearance. 

2. Effect of Concentration of Syrup. Prepare enough of each of the 
following syrups to fill one can of peaches: Balling (water), 10, 20, 
40, 60 Balling, see Table IV. Prepare enough fruit to fill five cans 
and weigh both the empty and filled cans. Heat each syrup to boiling; 
fill into the respective cans and seal. Sterilize for the length of time 
indicated in Table VI; remove the cans and chill in water. Allow to 
stand about one week. Determine the weight of drained fruit from each 
can and the volume and Balling of the syrup. Carefully compare the 
appearance, texture and flavor of the fruit from the different cans. 

3. Effect of Type of Container on Quality of Canned Fruit. Weigh 
one each of the several types of containers, such as sanitary, solder-top 
and wax-top cans and glass jars. Fill each with peaches and weigh. 
Prepare a syrup of 30 Balling. Heat this to boiling and fill the glass 
jars to overflowing and the cans to within about a quarter of an inch of 
the top. Exhaust the solder-top and sanitary cans in live steam for 5 
minutes before sealing. Sterilize, store and examine as in Assignment 
III C 2. 

A. Sealing Solder-Top Cans. Caution. Do not fill the cans above 
one-quarter inch below the cap. 

9 



10 



LABORATORY MANUAL OF 



(a) Wipe the groove dry of all syrup and juice. 

(b) Apply the cap and wipe the groove and edge of the cap with a 
small brush dipped in soldering fluid. 

(c) Dip a hot well-tinned soldering steel momentarily in soldering 
fluid, apply to the can and melt a little solder in the groove. 




B 



D 



FIG. 3. A, Coring knife; B, Pitting spoon; C, Cutting knife, and D, Peeling knife. 

(d) Revolve the hot steel to distribute the solder evenly. 

(e) Press down on the center rod, and raise the steel a few seconds 
to permit the solder to harden. 

(/) After exhausting the can wipe the vent hole and seal with a drop 
of solder applied with a well-tinned tipping steel. See Fig. 4. 

B. Sealing a Sanitary Can. (a) Place the lid on the can and set 



FRUIT AND VEGETABLE PRODUCTS 



11 




FKJ. 4. Sealing a solder top can; A. Wiping the groove; B. Applying soldering fluid; 
C. Melting solder in groove; D. Sealing on cap; E. Allowing solder to harden; F. Solder- 
ing vent hole (tipping). 



12 



LABORATORY MANUAL OF 



the can on the turn table. Raise the turn table, by swinging the raising 
lever slowly toward the operator until it will go no farther. Give the 

(b) Turn the crank rapidly and at the same time push the seaming 
roll lever very slowly away from the operator to bring roll Number 1 
against the top of the can until it will go in no farther. 

(c) Continue turning the crank rapidly and pull the seaming roll 
leveft-stewly toirtird the operator until it will go no further, (live the 
crank several more turns and remove the sealed can. See Figs. 5 and 6. 




FIG. 5. Hand power sealer for sanitary cans. 

C. Place the covers on the wax top cans, but do not seal with wax 
until after sterilization. 

D. Place rubber rings and covers on the glass jars, but do not seal 
tightly until after sterilization. 

4. Effect of Kind of Sugar. Prepare syrups of 30 Balling from 
several kinds of syrup, such as highest quality of glucose syrup, refined 
malt syrup, sorghum syrup, and as controls, 30 Balling syrups from 
cane sugar and beet sugar. Fruit juices may also be used instead of 



FRUIT AND VEGETABLE PRODUCTS 



13 



syrup. Can peaches in these syrups, sterilize, store, and examine as 
directed under Paragraph 2. 

5. Effect of Temperature. Prepare four cans of peaches, weighing 
the fruit placed in each can. Add a boiling 20 Balling syrup and seal. 

Heat at the following temperatures for the times indicated: 

165F. for 30 minutes 
185F. for 25 minutes 
212 F. for 20 minutes 
230F. for 15 minutes (under pressure) 



Compound Giiket 





fir* Optrition Roll 




Stand Opwition Roll 



FIG. 6. Sealing a sanitary can. 

Cool, store and examine as in Paragraph 2. If blackberries, straw- 
berries or raspberries are available, repeat the above tests with one of 
these fruits. 

6. Effect of Exhausting. Fill three cans with peeled, cored and quar- 
tered apples and add cold water to fill the cans to \'\ inch from the top. 
Seal Can No. 1. Heat Can No. 2 in water at 180F. for 6 minutes and 



14 LABORATORY MANUAL 

seal. Heat Can No. 3 in boiling water 6 minutes and seal. Sterilize the 
three cans for the time given in Table VI. Store the cans for 2 weeks 
and examine carefully as follows: 

Determine the vacuum in each can by means of a vacuum can tester. 
Open the cans and compare the amount of corrosion of the tin in each, 
especially at the water line near the top of the can. Compare the three 
samples as to appearance, flavor and texture. 

Suggestions: 

1. If apples are used the peelings and cores should be weighed, dried, 
again weighed, and the product retained for subsequent use in jellies or 
preserves. Pits should be weighed, dried and retained for the preparation 
of sweet and bitter almond oils. 

2. When several syrups of different strengths are required it is con- 
venient to make a sufficient quantity of 60 per cent, syrup and then 
dilute portions of this to the required strengths in accordance with the 
proportions given in Table IV. 

TABLE IV. PREPARATION OP SYRUPS FOR CANNING 

To make 5 gallons of 60 per cent syrup take 32 Ibs., 3 oz. (14.6 Kilograms) of sugar 
and 2 gals., 2 qts. and y<i pt. (9754 cubic centimeters) of water. 

896 c.c. 60 per cent syrup plus 105 c.c. water gives 1,000 c.c. 55 per cent syrup 
796 c.c. 60 per cent syrup plus 205 c.c. water gives 1,000 c.c. 50 per cent syrup 
701 c.c. 60 per cent syrup plus 301 c.c. water gives 1,000 c.c. 45 per cent syrup 
609 c.c. 60 per cent syrup plus 393 c.c. water gives 1,000 c.c. 40 per cent syrup 
522 c.c. 60 per cent syrup plus 480 c.c. water gives 1,000 c.c. 35 per cent syrup 
438 c.c. 60 per cent syrup plus 564 c.c. water gives 1,000 c.c. 30 per cent syrup 
357 c.c. 60 per cent syrup plus 645 c.c. water gives 1,000 c.c. 25 per cent syrup 
280 c.c. 60 per cent syrup plus 722 c.c. water gives 1,000 c.c. 20 per cent syrup 
206 c.c. 60 per cent syrup plus 796 c.c. water gives 1,000 c.c. 15 per cent syrup 
134 c.c. 60 per cent syrup plus 866 c.c. water gives 1,000 c.c. 10 per cent syrup 



ASSIGNMENT IV. PRACTICE IN FRUIT CANNING 

Materials. At least five pounds each of firm ripe fruits such as 
apples, apricots, plums, cherries, pears and berries. 

Procedure : 

1. Preparation. Weigh the fresh fruit and prepare for canning as 
follows : 

Apples: Peel and core by mechanical peeler. Trim and quarter by 
hand. Hold in 3 per cent, brine to prevent darkening. 

Apricots: Cut in half and remove pit. Make a clean cut on line 
of suture. Do not break or tear edges of halves. 

Berries: Sort out defective berries, stems and leaves. Stem straw- 
berries. 

Cherries: Remove stems. If desired, pits may be removed by small 
hand pitting machine. 

Grapes: Remove all stems and defective berries. 

Peaches: Halve and pit as for apricots. Peel as described in 
Assignment III. 

Pears: Hand peel, halve, core and stem. Hold in 3 per cent, brine 
to prevent darkening. 

Plums: Remove stems and defective fruits. 

Weigh the prepared fruit in each case and calculate the percentage 
loss in preparation. Wash all prepared fruit thoroughly. 

2. Grading: 

A. Quality: Sort the fruit according to quality to conform as nearly 
as possible to the five grades given in Table I. 

B. Size: Peaches, apricots, cherries, grapes and plums are graded 
for size by a series of vibrating screens, containing circular openings of 
the average sizes given in Tabic V. Because of their shape pears are 
graded by hand. If a mechanical grader is not available, grading may 
be accomplished by use of a board containing holes of the proper 
diameter. 

3. Filling and Syruping. Fill the cans with fruit and add the proper 
degree of syrup for each grade as specified in Table I. 

4. Exhausting and Scaling. Exhaust the filled cans in live steam or 
boiling water for 5 minutes. Seal the cans immediately after exhausting. 

5. Sterilizing and Cooling. Sterilize the cans in accordance with the 
time periods given in Table VI. Chill the cans in cold water and store 
for future examination. 

15 



16 



LABORATORY MANUAL 



6. Examination. After one week or longer open the cans and ex- 
amine as directed in Assignment I. Compare the results with the data 
given in Tables I and II. 

Suggestions. Apricot and cherry pits should be air-dried, weighed 
and retained for the preparation of fruit kernel oils in Assignment XXVI. 

TABLE V. AVERAGE DIAMETERS OP VARIOUS GRADES OP CANNED FRUITS 
(Thirty-Seconds of an Inch) 



Fruit 


Fancy 


Choice 


Stand. 


Fruit 


Fancy 


Choice 


Stand. 


Apricots 


56/32 
29/32 
26/32 
26/32 


54/32 
28/32 
25/32 
25/32 


50/32 
22/32 
22/32 

24/32 


Peaches 


76/32 
56/32 
8-10* 


64/32 
50/32 
10-12* 


56/32 
42/32 
15-17* 


Cherries, Royal Anne . 
Cherries, Black 


Plums, Green Gage 
Pears, Bartlett. . . . 


Grapes, Muscat 





* Number per No. 2J^ Can. 
TABLE VI. APPROXIMATE TIME REQUIRED FOR STERILIZATION OF FRUITS AT 212 F 



Fruit 


No. 1 Tall 
Cans 


No. 2H, 
No. 3 and 
Wax Top Cans 


No. 10 Cans 


Quart Glass 
Jars 


Apples 


Minutes 

10 


Minutes 

10 


Minutes 

15 


Minutes 

20 


Apricots 


8 


15 


25 


20 


Blackberries 


8 


12 


25 


20 


Cherries 


15 


20 


30 


30 


Currants 


8 


12 


25 


20 


Figs 


60 


60 


70 


75 


Gooseberries 


8 


12 


25 


20 


Grapes 


8 


10 


25 


20 


Loganberries 


8 


12 


25 


20 


Oranges 


8 


10 


25 


15 


Peaches (soft) 


15 


20 


40 


25 


Peaches (firm) 


20 


25 


40 


30 


Pears 


20 


25 


40 


30 


Plums 


10 


14 


25 


20 


Prunes (fresh) 


10 


12 


25 


20 


Raspberries 


8 


12 


25 


20 


Rhubarb 


8 


12 


25 


20 


Strawberries 


8 


12 


25 


20 













ASSIGNMENT V. DETERMINATION OF THE GRADE OF 
COMMERCIALLY CANNED VEGETABLES 

Materials. One can each of the different grades of several important 
vegetables, such as tomatoes, corn, peas, string beans and asparagus. 

Procedure: 

1. Weigh the can. 

2. Ascertain the vacuum within the can by piercing the top of the 
can with a vacuum can tester. 

3. Open the can and empty the contents on a piece of %-inch mesh 
screen and drain for 2 minutes. Weigh the drained vegetable and meas- 
ure the volume of brine. Weigh the empty can. Compare the drained 
weights with those given in the Appendix, Table XV. 

4. In asparagus, count the number of spears; in peas or beans, ascer- 
tain the average diameter of the pieces. 

5. Compare the different grades of each vegetable for (a) color, 
(6) odor, (c) condition of pieces; that is, whether whole or broken; 
prime, over-mature or immature; soft or firm; (d) flavor. 

6. Note the clearness, color and general appearance of the brine. 
Determine its specific gravity or Baume degree. If desired, the amount 
of salt in the brine may be determined as outlined on page 98 of Ap- 
pendix. Where a sugar brine has been used the concentration of sugar 
may be determined as described on page 100 of Appendix. 

7. Note the condition of the interior of the can. 

Suggestions. The commercial grades of canned vegetables are not 
as well standardized as those of canned fruits. The following specifica- 
tions describe the most common commercial grades and form a guide 
in determining the grade of the samples examined. 

GRADES OF CANNED VEGETABLES 
Corn: 

A. Styles: 

1. Maine style thick and creamy consistency without separation of 
liquid. (Can not be labelled "Maine Style" unless canned in Maine.) 

2. Maryland style whole grains in clear brine. 

B. Grades: 

1. Fancy young, tender, no tough grains, medium moist, free from 
silk, cob or husk. Flavor of young corn. Only slightly darker than 
natural product. 

17 



18 LABORATORY MANUAL OF 

2. Extra Standard corn with some slight defect, but better than 
standard grade as described below. 

3. Standard reasonably tender, only slightly brown in color, nearly 
free from silk, cob or husk. Only slight "cooked taste." 

4. Second hard, tough grains of poor flavor or appearance. 

Peas : 

A. Varieties: 

1. Early Peas small, smooth, round. 

2. Sweet Peas wrinkled, irregular in shape, later maturing, distinctly 
sweet. 

B. Size Grades: 

No. Common Name Diameter in Inches 

1 Petit Pois Below 9/32 

2 Extra Sifted 9/32 to 10/32 

3 Sifted 10/32 to 11/32 

4 Early June 11/32 to 12/32 

5 Marrowfat 12/32 to 13/32 

6 Telephone Over 13/32 

C. Quality Grades: 

1. Fancy young, succulent, fairly uniform in size and color, reason- 
ably clear liquor, no flavor defects. 

2. Standard less succulent, green, mellow consistency, uniform in 
size and color, reasonably clear liquor, fairly free from flavor defects. 

3. Seconds over-mature, not fully ripened or lacking in other re- 
spects the qualifications of standard peas. 

Beans (string, green or wax): 

A. Size Grades: 

No. 1, less than 12/64 inch diameter | , , , , 

No. 2, 12/64 to 14/64 inch diameter J 

No. 3, 14/64 to 17/64 inch diameter } 

No. 4, 17/64 to 20/64 inch >Cut beans 

No. 5, over 20/64 inch j 

B. Quality Grades: 

1. Fancy- prime beans, uniform and tender in quality, good flavor 
and color, carefully handled and canned, clear brine. 

2. Extra Standard not equal to fancy grade because of a slight 
defect. 

3. Standard good field run beans of less uniform selection. May be 
slightly discolored or broken. 

4. Seconds wholesome beans which may be coarse, tough, poorly 
stringed or with foreign flavor. 



FRUIT AND VEGETABLE PRODUCTS 



19 



Tomatoes: 

A. Types: 

1. Solid Pack Tomatoes peeled and cored tomatoes canned whole 
or in large pieces without addition of any liquid. 

2. Tomatoes in Puree peeled and cored tomatoes, generally smaller 
pieces to which has been added puree made from whole tomatoes or from 
trimmings of tomatoes. 

B. Grades: 

1. Extra Fancy ripe fruit of uniform red color, well-developed flavor 
and fleshy body. Mostly whole tomatoes free from peel, cores or defects. 

2. Extra Standard ripe fruit of fairly fleshy body, good flavor and 
few yellow or green pieces. Mostly large pieces, well peeled, cored and 
trimmed. 

3. Standard Tomatoes fully matured, sound fruit of fair body and 
flavor. Broken pieces of irregular color, but well peeled, cored and 
trimmed. 

4. Seconds a mixture of green, immature pieces and soft, over-ripe 
tomatoes. 

Asparagus: 

California asparagus is graded by hand according to the number of 
spears per can. Each size grade is further graded into white and green 
asparagus. 



Grade 


Size of Can 


Xo. Spears per Can 


Giant 


2*4 Square* 


8 to 12 


Colossal 


2]^, Square 


13 to 16 


Mammoth 


2^2, Square 


17 to 24 


Mammoth 


1, Square Tips* 


21 to 30 


I >H rut 


2\^, Square 


25 to 34 


Large 


1, Square Tips 


31 to 40 


Medium 


2]/z, Square 


35 to 44 


Medium 


1, Square Tips 


41 to 60 


Small 


2H, Square 


45 to 60 


Small 


1, Square Tips 


61 to 80 


Tiny 


1, Square Tips 


81 to 100 









* No. 1, Square Can is 3X3HX3>6 inches; No. 2J& Square Can is 3X3^X6^ inches. 

Beets: 

Beets should be tender and without large vascular zones and of a 
uniform deep red color throughout. 

1. Small below 1 inch diameter. 

2. Medium. 1 to 1M> inches diameter. 

3. Large I 1 /* to 2 inches diameter. 

4. Very large over 2 inches diameter (cut beets). 



ASSIGNMENT VI. EXPERIMENTAL CANNING OF 
VEGETABLES 

Materials. A vegetable of high acidity, such as tomatoes or rhu- 
barb, and a vegetable of low acidity, such as string beans, peas, or corn. 

Procedure : 

1. Preparation. Prepare the raw material for canning as directed in 
Assignment VII. 

2. Effect of Composition of Vegetables on Sterilizing Temperature. 
Prepare three cans each of an acid vegetable (e. g., tomatoes) and of a 
vegetable of low acidity. Exhaust the cans in hot water at 175 F. for 
about 6 minutes; seal hot. Heat one can of each in water at 175 to 
180F. for 30 minutes; one can of each in boiling water for 30 minutes 
and one can of each at 240F. for 15 minutes. Remove the cans in each 
instance and chill in water. Place the cans in an incubator at 90 to 
100F. for 2 weeks and note the condition of the cans and contents. 

3. Effect of Composition of Brine. Prepare six cans of a vegetable 
of low acidity, such as peas or string beans. Fill Can No. 1 with boiling 
2 per cent, brine; No. 2 with boiling 4 per cent, brine; No. 3 with a 
boiling 6 per cent, brine; No. 4 with 2 per cent, brine acidified to 0.1 
per cent, acidity with lemon juice or citric acid; No. 5 with 2 per cent, 
brine acidified to 0.2 per cent, citric acid; and No. 6 with 2 per cent, 
brine acidified to 0.15 per cent, acetic acid with distilled vinegar. (See 
page 98 in Appendix for determination of acid.) Exhaust all the cans 
for 5 minutes and seal hot. Heat all the cans in boiling water for 30 
minutes. Remove and cool in water. Incubate all the cans at 90 to 
100F. for 2 weeks and examine. 

4. Critical Temperature. Prepare five cans each of tomatoes and 
string beans; add 2 per cent, brine to the string beans; exhaust all the 
cans for 5 minutes and seal. Heat the cans for 1 hour as follows: One 
can at 212F.; one can at 240F.; one can at 250F. Cool all the cans 
in water. After 48 hours compare the quality of the different lots in 
respect to texture, color, odor and flavor. 

5. Intermittent Sterilization. Prepare 8 cans of a vegetable of low 
acidity in 2 per cent, brine. Add spore-bearing cultures of Bacillus 
subtilis or other harmless spore-bearing bacteria. Exhaust 5 minutes 
and seal. Place two cans in cold water and heat to boiling. Boil one 
hour. Similarly, boil two cans l l /2 hours. Similarly, heat two cans in 

20 



FRUIT AND VEGETABLE PRODUCTS 21 

water until the water boils and boil for 30 minutes each of 2 successive 
days. Similarly, heat two cans for 30 minutes on each of three succes- 
sive days. Place all cans in an incubator at 90 to 100F. for 2 weeks 
and then examine. 

Caution. Spoiled cans of vegetables may be poisonous and must not 
be tasted. 

Suggestions. The presence of thermophilic bacteria which have sur- 
vived the process of sterilization can be ascertained by incubating cans 
at 130F. for two weeks. The cans will become "flat sours" if thermo- 
philic bacteria have been active. 



ASSIGNMENT VII. PRACTICE IN VEGETABLE CANNING 

Materials. At least five pounds each of such vegetables as corn, 
peas, pumpkin, sweet potatoes, asparagus and spinach. 

Procedure: 

1. Preparation. Prepare the vegetables as directed below, and deter- 
mine the loss in preparation. 

Asparagus. Cut to proper length for containers. 

Corn. Carefully remove all husk and silk as well as worm-eaten 
portions. Cut kernels from cob with a sharp, thin-bladed knife and 
scrape cobs. 

Beans (Green, String or Wax). Snip the ends of beans and remove 
strings. 

Beets. Cut off leaves, retaining 1 inch of stems. Do not cut off 
roots. Heat in retort at 220F. for 20 to 25 minutes, or in boiling water. 
Remove stems, roots and skins. 

Peas. Shell from pods. 

Peppers or Pimientos. Place in a wire basket and dip in a kettle 
of boiling cottonseed oil (about 400F.) until peel separates, about 1 to 4 
minutes. Wash and cool in water. Strip off loosened peel, cut out stem 
and scoop out core and seeds, carefully preserving the flesh in one piece. 

Pumpkin. Wash thoroughly; remove stems; chop into large pieces; 
place in pans in a retort at 240F. for 20 minutes. Separate pulp from 
skins, seeds and fiber by rubbing through a fine screen. Concentrate to 
a thick consistency in a steam-jacketed kettle. The specific gravity 
should be about 1.06 to 1.08. 

Potatoes, Sweet. Heat in a retort at 240F. for 9 to 12 minutes. 
Slip the skins off by hand. 

Spinach. Cut off crowns, heavy stalks and yellow leaves. Wash 
very thoroughly to remove adhering soil. 

Tomatoes. Remove decayed portions. Wash thoroughly. Heat in 
boiling water or steam about one minute. Chill in cold water. Remove 
peels and cores. 

2. Grading. Grade asparagus, beans, beets and peas for size and 
quality by reference to Assignment V. 

3. Blanching and Pre-cooking. Blanch asparagus, string beans, peas 
and spinach in boiling water as directed in Table VII. The time of 
blanching is regulated by the size and maturity of the product. Thor- 
ough washing should always follow blanching. 

22 



FRUIT AND VEGETABLE PRODUCTS 



23 



Corn. Add to the cut corn a sweet brine containing about 4 per cent, 
sugar and 2.5 per cent, salt, at the rate of 5 ounces per No. 2 can. Mix 
thoroughly and cook in a steam- jacketed kettle until tender and the 
liquid and the kernels no longer separate. 

4. Filling and Brining. Corn, pumpkin and sweet potatoes: The 
cans should be filled with the hot vegetables without addition of brine. 
Pimientos and peppers are packed solidly and may be canned with or 
without brine. Other vegetables may be placed in the cans cold and 
the cans filled with hot brine of the composition given in Table VII. 

Use lacquered cans for beets, pumpkin and sweet potatoes. 

5. Exhausting and Sealing. Exhaust the filled cans in live steam 
for the periods given in Table VII. Seal immediately after exhausting. 

6. Sterilization and Cooling. Sterilize the hot sealed cans at the 
temperatures and times given in Table VII. Cool thoroughly in water 
immediately after sterilizing. The sterilizing periods and temperatures 
given in Table VII vary with the maturity of the products and size of 
the can. The periods given are for non-agitating sterilizers. 

7. Storage and Examination. Store for about two weeks and com- 
pare the quality with that of samples of similar commercial canned 
products. 

TABLE VII. CANNING SCHEDULE FOR VEGETABLES 



Vegetable 


Steaming or 
Blanching 


Composition of 
Brine 


Exhaust- 
ing 


Sterilizing No. 2 
or No. 3 Cans 


Temp. 


Minutes 


Per cent 
Salt 


Per cent 
Sugar 


Minutes 
at 212 


Temp. 


Minutes 


Asparagus 


212 
212 
220 


3- 5 
1- 9 
20 


2 

lK-2> 
0-2^ 

2-X 

2 

or 2 




8-12 
5- G 
5- 6 


233 
240 
245 
250 
240 

212 
212 
250 
252 
212 


30 
30 
60 
75 
40 

35 
180 
90 
50 
30 


Beans, string. . . 








4 
0-3 


Peas 


212 

400* 
240 
240 
212 
212 


3-15 

1- 4 
9-12 
20 
3- 6 

y^ 


6-11 

3-13 
12-18 


Peppers or 
Pimientos. . . . 
Potatoes, Sweet . 










3-tf 




8-11 
8-10 













Cottonseed Oil. 



24 LABORATORY MANUAL 

TABLE VIII. RELATION OP STEAM PRESSURE TO TEMPERATURE 



Pressure- Pounds 
per Square Inch 


Temperature, 
Fahrenheit 


Pressure-Pounds 
per Square Inch 


Temperature, 
Fahrenheit 


1 


215.2 


9 


236.6 


2 


218.3 


10 


238.8 


3 


221.3 


11 


241.0 


4 


224.2 


12 


243.1 


5 


226.9 


13 


245.3 


6 


229.5 


14 


247.3 


7 


231.9 


15 


249.1 


8 


234.3 


16 


250.7 



ASSIGNMENT VIII. EXAMINATION OF TOMATO 

PRODUCTS 

Materials. Samples of tomato puree, paste and catsup. 

Procedure : 

1. Determination of Total Solids. A. Official Method: Place from 
2 to 4 grams of the well-mixed sample in an accurately weighed flat- 
bottomed dish about 2% inches in diameter, spreading thinly. Accu- 
rately weigh the dish and sample. Place in a vacuum oven at 70C. 
(158F.) for 4 hours in a vacuum equivalent to 28 to 29 inches mercury. 
Remove from the oven and weigh immediately. The loss in weight 
divided by the weight of sample multiplied by 100 gives the percentage 
of water in the sample, which subtracted from 100 gives the percentage 
of total solids. 

B. Tentative Method: In the absence of a vacuum oven, weigh 10 
grams of the well-mixed sample into a weighed flat-bottom dish Evapo- 
rate to dryness on a steam bath and dry 4 hours in a water- or steam- 
jacketed oven at 95 to 100C. (203 to 212F.). The percentage of 
total solids thus obtained should be multiplied by the factor 1.085 to give 
the true percentage. 

2. Determination of Specific Gravity. A. By Pycnometer: Weigh a 
dry and empty 50-c.c. pycnometer. Fill with distilled water at 20C. 
and weigh. The difference between these two weights gives the volume 
of the pycnometer or A. Empty the pycnometer and weigh. Add about 
10 grams of well-mixed sample and weigh. The difference between these 
two weights gives the exact weight of the sample or B. Fill with distilled 
water at 20C., weigh and subtract the original weight of the dry pyc- 
nometer. Call this C. C minus B = D, the volume of water required 
to fill the pycnometer after addition of the sample. A minus D gives E, 
the volume of water displaced by the sample. B divided by E gives the 
specific gravity of the sample. 

B. By Hydrometer: Fluid samples such as light puree can be filtered 
through cloth or filter paper and the specific gravity of the clear filtrate 
obtained by means of a specific gravity hydrometer at 20C. By refer- 
ence to Table IX the specific gravity of the original sample may be 
obtained. 

3. Relation of Total Solids to Specific Gravity. Table IX gives the 

25 



26 



LABORATORY MANUAL OF 



relation between the specific gravity of tomato puree, the specific gravity 
of the filtrate and total solids. The table does not apply to tomato 
catsup or other products to which foreign materials have been added. 

4. Microscopical Examination. A. Estimation of Molds: Fit the mi- 
croscope with a 10X (1 inch) eye piece and 16-mm. (2/3 inch) objective. 
Place a stage micrometer under the objective and adjust the draw tube 
until the field of vision is 1.4 mm. in diameter. This equals an area of 
1.5 square mm. The larger divisions on the stage micrometer are 0.1 
mm. and the smaller divisions .01 mm. apart. If a stage micrometer is 



FIG. 7. Rulings on hsemetimeter used in examining tomato products. 

not available a hsemetimeter may be used to measure the diameter of 
the field. Each small square of the haemetimeter is 0.05 mm. in diame- 
ter. The magnification should be 90 to 100 diameters. 

Spread a drop of the well-mixed sample on the disc of a Howard 
counting chamber. Cover with the heavy cover-glass and press it evenly 
against the slide. This forms a layer of material one millimeter thick. 

Examine carefully 50 separate fields for mold filaments. This will 
usually require two mountings. All fields showing mold filaments aggre- 
gating one-sixth or more of the diameter of the field are considered 
positive. Multiply the number of positive fields by 2 to obtain "Per- 
centage of Fields Showing Mold." In the examination of tomato paste 



FRUIT AND VEGETABLE PRODUCTS 27 

dilute the sample in the proportion of 2 c.c. of water to each gram of 
paste. 

B. Yeasts and Spores: Fit the microscope with a 10X (1 inch) eye 
piece and an 8-mm. (1/3 inch) objective. This gives a magnification of 
about 200 diameters, draw tube set at 160 mm. 

Dilute 10 c.c. of puree or catsup to 30 c.c. with water or paste 10 
grams to 90 c.c. Mix thoroughly and allow to settle a few minutes. 
Mount a drop of the settled liquid on the disc of a haemetimeter. Cover 
with a large cover-glass and press evenly against the slide. 

Count the number of mold spores and yeast cells in 200 of the small 
squares of the haemetimeter represented by eight blocks of 25 squares 
each marked A in Fig. 7. 

Each of the smallest squares is .05 mm. x .05 mm., or .0025 square 
mm. in area. Since the liquid is 0.1 mm. in depth the volume of liquid 
above each square is .00025 cubic mm. Therefore the volume above 200 
squares is .00025 x 200 = .05 cubic mm. or 1/20 cu. mm. Since the sam- 
ple was diluted to one-third its original concentration, the above estima- 
tion represents the number of "Yeasts and Spores per 1/60 cu. mm." 

C. Bacteria (Howard Method) : Fit the microscope with a 12.5X 
eye piece and 4-mm. (1/6 inch) objective. This combination gives a 
magnification of 570 at draw tube setting of 160 mm. 

Use the same mounting as for yeasts and spores. Count the number 
of distinct rod-shaped bacteria in 25 small squares; i. e., five groups of 
five small squares each represented by letter B in Fig. 7. Do not count 
spherical forms. Mount two more samples and repeat the examination 
and determine the average number of bacteria to the small square. 

Since one small square represents .00025 i. e., 1/4,000 cubic milli- 
meters of liquid one bacterium to a square represents 4,000 per cu. mm., 
or 4,000,000 per cubic centimeter. Since the sample was diluted to one- 
third its original concentration, one bacterium to a square represents 
12,000,000 bacteria per cubic centimeter of original sample. 

D. Bacteria (Miller Modification) : Transfer 20 c.c. of the sample 
to a 100-c.c. beaker; add 2 c.c. Loeffler's methylene blue stain; boil 3 
minutes; add 2 c.c. Ziehl-Nielsen carbol-fuchsin stain; boil 3 minutes; 
allow to cool slightly; add 3 to 4 drops of formalin; make up to 60 c.c. 
with water; mix and allow to settle. Examine as in Assignment VIII 
4 C. The staining renders the bacteria more clearly visible. 

Suggestions: 

1. Tomato products which, upon microscopic examination by the 
above methods, show 66 per cent, or more positive mold fields, or yeast 
and spores in excess of 125 per 1/60 cu. mm. or bacteria in excess of 
100,000,000 per c.c., are subject to seizure and condemnation under the 



28 



LABORATORY MANUAL OF 



TABLE IX. RELATION BETWEEN TOTAL SOLIDS AND SPECIFIC GRAVITY OF TOMATO 

PULP AND FILTRATE* 



Per cent 
Solids 
in Pulp 


Specific Gravity 
at 20 C. 


Per cent 
Solids 
in Pulp 


Specific Gravity 
at 20 C. 


Per cent 
Solids 
in Pulp 


Specific Gravity 
at 20 C. 


Pulp 


Filtrate 


Pulp 


Filtrate 


Pulp 


Filtrate 


3.42 


1.0150 


1.0133 


5.38 


1.0228 


1.0209 


7.34 


1.0308 


1.0285 


3.47 


1.0152 


1.0136 


5.44 


1.0230 


1.0211 


7.40 


1.0310 


1.0287 


3.53 


1.0155 


1.0138 


5.49 


1.0233 


1.0213 


7.45 


1.0313 


1.0290 


3.58 


1.0157 


1.0140 


5.55 


1.0235 


1.0216 


7.51 


1.0315 


1.0292 


3.64 


1.0159 


1.0142 


5.60 


1.0237 


1.0218 


7.56 


1.0317 


1.0294 


3.70 


1.0161 


1.0144 


5.66 


1.0240 


1.0220 


7.62 


1 . 0320 


1.0296 


3.76 


1.0163 


1.0146 


5.72 


1.0242 


1.0223 


7.68 


1.0322 


1.0298 


3.81 


1.0166 


1.0149 


5.77 


1.0244 


1.0225 


7.74 


1.0324 


1.0300 


3.87 


1.0168 


1.0151 


5.83 


1.0247 


1.0227 


7.79 


1.0326 


1.0303 


3.92 


1.0170 


1.0153 


5.88 


1.0249 


1.0229 


7.85 


1.0329 


1.0305 


3.98 


1.0172 


1.0155 


5.94 


1.0251 


1.0231 


7.90 


1.0331 


1.0307 


4.03 


1.0174 


1.0157 


6.00 


1.0253 


1.0233 


7.96 


1.0333 


1.0309 


4.09 


1.0177 


1.0160 


6.05 


1.0256 


1.0235 


8.02 


1.0336 


1.0311 


4.15 


1.0179 


1.0162 


6.11 


1.0258 


1.0238 


8.07 


1 . 0338 


1.0313 


4.20 


1.0181 


1.0164 


6.16 


1.0260 


1.0240 


8.12 


1.0340 


1.0315 


4.26 


1.0183 


1.0166 


6.22 


1.0263 


1.0242 


8.18 


1.0342 


1.0318 


4.31 


1.0185 


1.0168 


6.28 


1.0265 


1.0244 


8.24 


1.0345 


1.0320 


4.37 


1.0188 


1.0170 


6.33 


1.0267 


1.0246 


8.30 


1.0347 


1.0322 


4.43 


1.0190 


1.0173 


6.39 


1.0270 


1.0249 


8.35 


1.0349 


1.0324 


4.48 


1.0192 


1.0175 


6.45 


1.0272 


1.0251 


8.40 


1.0352 


1.0326 


4.54 


1.0194 


1.0177 


6.50 


1.0274 


1.0253 


8.46 


1.0354 


1.0328 


4.59 


1.0197 


1.0179 


6.56 


1.0276 


1.0255 


8.52 


1.0356 


1.0331 


4.65 


1.0199 


1.0181 


6.61 


1.0279 


1.0257 


8.57 


1.0358 


1.0333 


4.71 


1.0201 


1.0183 


6.67 


1.0281 


1.0259 


8.63 


1.0361 


1.0335 


4.76 


1.0203 


1.0185 


6.72 


1.0283 


1.0261 


8.68 


1.0363 


1.0337 


4.82 


1.0205 


1.0188 


6.78 


1.0285 


1.0263 


8.74 


1.0365 


1.0339 


4.87 


1.0208 


1.0190 


6.84 


1.0288 


1.0266 


8.80 


1.0367 


1.0341 


4.93 


1.0210 


1.0192 


6.89 


1.0290 


1.0268 


8.86 


1 . 0370 


1.0344 


4.99 


1.0212 


1.0194 


6.95 


1.0292 


1.0270 


8.91 


1.0372 


1.0346 


5.04 


1.0215 


1.0196 


7.01 


1.0294 


1.0272 


8.96 


1.0374 


1.0348 


5.10 


1.0217 


1.0198 


7.06 


1.0297 


1.0274 


9.02 


1.0277 


1.0350 


5.16 


1.0219 


1.0200 


7.12 


1.0299 


1.0277 


9.08 


1.0379 


1.0352 


5.21 


1.0222 


1.0203 


7.17 


1.0301 


1.0279 


9.14 


1.0381 


1.0354 


5.27 


1.0224 


1.0205 


7.23 


1.0304 


1.0281 


9.19 


1.0383 


1.0357 


5.33 


1.0226 


1.0207 


7.28 


1.0306 


1.0283 


9.25 


1.0386 


1.0359 



*According to Bigelow and Fitzgerald in Journal of Industrial and Engineering 
Chemistry, vol. 7, No. 7, page 602. July, 1915. 



FRUIT AND VEGETABLE PRODUCTS 
TABLE IX. Continued 



29 



Per cent 
Solids 
in Pulp 


Specific Gravity 
at20C. 


Per cent 
Solids 
in Pulp 


Specific Gravity 
at 20 C. 


Per cent 
Solids 
in Pulp 


Specific Gravity 
at 20 C. 


Pulp 


Filtrate 


Pulp 


Filtrate 


Pulp 


Filtrate 


9.30 


1.0388 


1.0361 


10.97 


1.0456 


1.0426 


12.65 


1.0524 


1.0491 


9.36 


1.0390 


1.0363 


11.02 


1.0458 


1.0428 


12.71 


1.0526 


1.0493 


9.42 


1.0393 


1.0366 


11.08 


1.0461 


1.0430 


12.77 


1.0528 


1.0495 


9.47 


1.0395 


1.0368 


11.14 


1.0463 


1.0433 


12.83 


1.0531 


1.0498 


9.53 


1.0397 


1.0370 


11.20 


1.0465 


1.0435 


12.88 


1.0533 


1.0500 


9.58 


1.0400 


1.0372 


11.25 


1.0467 


1.0437 


12.94 


1.0535 


1.0502 


9.64 


1.0402 


1.0374 


11.30 


1.0469 


1.0439 


12.99 


1.0538 


1.0504 


9.70 


1.0404 


1.0376 


11.36 


1.0472 


1.0441 


13.05 


1.0540 


1.0506 


9.75 


1.0406 


1.0379 


11.41 


1.0474 


1.0444 


13.10 


1.0542 


1.0508 


9.80 


1.0408 


1.0381 


11.47 


1.0476 


1.0446 


13.16 


1.0544 


1.0511 


9.86 


1.0410 


1.0383 


11.53 


1.0478 


1.0448 


13.22 


1.0547 


1.0513 


9.92 


1.0413 


1.0385 


11.59 


1.0481 


1.0450 


13.27 


1.0549 


1.0515 


9.97 


1.0415 


1.0387 


11.64 


1.0483 


1.0452 


13.32 


1.0551 


1.0517 


10.02 


1.0417 


1.0389 


11.70 


1.0485 


1.0454 


13.38 


1.0554 


1.0519 


10.08 


1.0419 


1.0392 


11.75 


1.0487 


1.0457 


13.44 


1.0556 


1.0521 


10.14 


1.0421 


1.0394 


11.81 


1.0490 


1.0459 


13.50 


1.0558 


1.0523 


10.19 


1.0424 


1.0396 


11.87 


1.0492 


1.0461 


13.55 


1.0560 


1.0525 


10.25 


1.0426 


1.0398 


11.93 


1.0494 


1.0463 


13.60 


1.0562 


1.0527 


10.30 


1.0428 


1.0400 


11.99 


1.0496 


1.0465 


13.66 


1.0565 


1.0529 


10.35 


1.0430 


1.0402 


12.05 


1.0499 


1.0467 


13.72 


1.0567 


1.0531 


10.41 


1.0433 


1.0404 


12.10 


1.0501 


1.0469 


13.78 


1.0569 


1.0533 


10.47 


1.0435 


1.0406 


12.15 


1.0503 


1.0471 


13.83 


1.0572 


1.0535 


10 52 


1.0437 


1.0409 


12.21 


1.0505 


1.0474 


13.89 


1.0574 


1.0537 


10 58 


1.0440 


1.0411 


12.26 


1.0508 


1.0476 


13.95 


1.0576 


1.0539 


10.64 


1.0442 


1.0413 


12.32 


1.0510 


1.0478 


14.01 


1.0579 


1.0241 


10 70 


1.0444 


1.0415 


12.37 


1.0512 


1.0480 








10.75 


1.0447 


1.0417 


12.43 


1.0515 


1.0482 








10.80 


1.0449 


1.0419 


12.49 


1.0517 


1.0484 








10.86 


1.0451 


1.0422 


12.55 


1.0519 


1.0487 








10.91 


1.0453 


1.0424 


12.60 


1.0522 


1.0489 









30 LABORATORY MANUAL 

Federal Pure Foods and Drugs Act of 1906. The same standards have 
been adopted by most states. 

Investigations have shown that with reasonable care and promptness 
in the sorting and washing of tomatoes, together with cleanliness in the 
care of equipment, it is readily possible to manufacture tomato products 
containing numbers of micro-organisms well below the legal limits. 

For a more detailed discussion of this subject consult U. S. Dept. Agr. 
Bull. 581. 

2. No legal standards for the specific gravity of tomato products 
have been adopted, but the following tentative standards have been sug- 
gested and are generally observed in commercial practice: 

Light tomato puree, 6.3 per cent, total solids = 1.026 spec, gravity. 
Medium tomato puree, 8.37 per cent, total solids 1.035 spec, gravity. 
Heavy tomato puree, 12.00 per cent, total solids = 1.050 spec, gravity. 
Tomato catsup, not less than 12 per cent, tomato solids. 

3. Benzoate of Soda. Thin catsups low in acetic acid are sometimes 
preserved with sodium benzoate, which is permitted by the Food and 
Drug Regulations if the presence of benzoate is declared on the label. 
The usual quantity is 0.1 per cent. The presence of this preservative 
can be detected by the method given in the Appendix, page 102. 



ASSIGNMENT IX. EXPERIMENTAL PREPARATION OF 

TOMATO PUREE 

Materials. About 50 pounds of field run tomatoes with at least 
one-third of the tomatoes showing mold. 

Procedure: 

1. Carefully separate the sound tomatoes from those showing mold. 
Wash the sound tomatoes. Crush and pulp these tomatoes without 
heating and divide the screened pulp into two portions. Concentrate one 
portion at once to a specific gravity of about 1.035 as directed in Sec- 
tion 1, Assignment X. Allow the other portion to stand for one day or 
overnight and then concentrate in the same way. 

2. Rinse but do not trim the moldy tomatoes and prepare from them 
puree of about 1.035 specific gravity as described in Section 1, Assign- 
ment X. 

3. Determine the amounts of mold and of bacteria in the three lots 
of puree as described in Assignment VIII. Compare the results obtained 
with the character of the raw material and the methods of handling. 

Suggestions. Save the tomato seeds as directed in Suggestions, 
Assignment X. 



31 



ASSIGNMENT X. PRACTICE IN THE PREPARATION OF 
TOMATO PRODUCTS 

Materials. Approximately 250 pounds of sound, smooth, evenly- 
ripened tomatoes of deep-red color, firm flesh and good flavor. 

Procedure: 

1. Medium Puree. Weigh accurately; sort carefully; trim and wash 
about 50 pounds of tomatoes. Determine the loss in trimming. 

Crush the tomatoes thoroughly and transfer to a steam-jacketed 
kettle or large aluminum pot and boil about three minutes. 

Pass the hot pulp through the finishing screen of a tomato pulper or 
rub through a very fine copper screen by hand to remove the seeds, skins 
and fiber. 

Return the pulp to the kettle or large pot and concentrate rapidly 
with constant stirring to a specific gravity of 1.035, determined as di- 
rected below. This specific gravity corresponds approximately to a 
concentration of 3 parts of raw pulp to 2 parts of puree. 

RAPID DETERMINATION OF SPECIFIC GRAVITY 

Filter a sample of the hot pulp through cheese cloth into a hydrome- 
ter cylinder packed in crushed ice and salt. Cool the filtrate rapidly to 
20C. (68F.) and determine the specific gravity by means of an accu- 
rate hydrometer or Westphal balance. Obtain the corresponding specific 
gravity of the puree from Table IX. 

Determine the volume of finished puree. Fill several 16-oz. bottles, 
plain sanitary cans and lacquered cans with the boiling-hot puree. Seal 
all containers immediately and invert, using crown caps for the bottles. 
Heat two of the plain cans in boiling water or steam for 30 minutes. 
Store all samples for subsequent examination. 

2. Puree for Catsup. Treat a carefully weighed quantity of toma- 
toes (about 50 pounds) as directed in Assignment X 1, but concentrate to 
a specific gravity of 1.060. Determine the yield by volume and by 
weight. 

Reserve one gallon of the concentrated puree for the preparation of 
catsup in Assignment X 3. Fill one-half of the remainder boiling hot into 
lacquered cans and one-half boiling hot into plain tin cans; seal at once; 
invert to cool and set aside for at least six weeks. Compare these sam- 

32 



FRUIT AND VEGETABLE PRODUCTS 33 

pies with those prepared according to Assignment X 1 for color, flavor and 
consistency. 

3. Tomato Catsup (Spiced Vinegar Process). To 435 c.c. of distilled 
vinegar of 10 per cent, acetic acid content ("100 grain" vinegar) and 
132 c.c. of water in a 1,000-c.c. flask add the following ingredients: 

Onions, peeled and chopped . . . 105 grams Allspice, whole 4.5 grams 

Garlic, peeled and chopped 1 gram Cayenne pepper, ground 1 gram 

Cloves, whole 4 grams Mace, not ground t gram 

Cinnamon, whole 7 grams 

Connect the flask to a reflux condenser or cover the mouth of the 
flask with a watch glass or Petri dish and allow to simmer for about one 
hour. Strain through cheese cloth. If the volume is less than 570 c.c. 
add water to restore to this volume. Dissolve in this hot spiced vinegar 
585 grams of sugar and 135 grams of salt. Add- this spiced vinegar to 
one gallon (3,785 c.c.) of puree of about 1.060 specific gravity. Stir 
thoroughly, heat to boiling and fill hot into 16-oz. crown-finish bottles. 
Seal at once and invert to cool. Heat two of the bottles in boiling water 
or steam for 30 minutes. 

Note the flavor, color, odor and consistency after six weeks' storage. 
A specific gravity determination may be made if desired. 

4. Tomato Catsup (by Direct Extraction of Spices). Place in a 
small cheese-cloth bag the same quantities of spices, onion and garlic 
as used in Paragraph 3. Tie the mouth of the bag and place it in three 
gallons of unconcentrated raw tomato pulp. Concentrate by boiling to 
about 1.060 specific gravity (approximately one gallon). Dissolve 585 
grams of sugar and 135 grams of salt in 435 c.c. of distilled vinegar 
(100 grain) and 132 c.c. water. Add this solution to the concentrated 
hot puree. Stir thoroughly, heat to boiling, remove the sack of spices 
and fill the catsup hot into 16-oz. crown-finish bottles. Determine the 
approximate yield. Store and examine as under Assignment X 3. 

5. Chili Sauce. To 380 c.c. of distilled vinegar (100 grain) in 1,000 
c.c. flask add the following ingredients: 

Onions, chopped 363 grams 

Allspice, whole 5.6 grams 

Cloves, whole 5.6 grams 

Cinnamon, sticks 6.6 grams 

and allow to simmer for about one hour as in Assignment X 3, and strain 
through cheese cloth. Dissolve in the strained liquid 636 grams sugar 
and 136 grams of salt. 

Place 8,400 grams whole peeled tomatoes in a pot and concentrate 
to approximately 4,000 c.c. Then add 5.6 grains ground cayenne pepper 
and 1.4 grains ground mustard. Concentrate to about 3,400 c.c. and add 



34 LABORATORY MANUAL 

the spiced vinegar. Stir thoroughly. Heat to boiling and seal hot in 
glass fruit-jars. Pasteurize 40 minutes in water at 185F. Store and 
examine as under Assignment X 3. 

6. Hot Sauce (Spanish Style). To 6,205 c.c. of raw non-concentrated 
pulp (from a tomato pulper) add the following ingredients, finely 
ground : 

Onions 74 grams 

Ground chili peppers 112 grams 

Garlic 2.3 grams 

Concentrate to about 3,785 c.c. Add 2.5 grams ground cayenne 
pepper mixed with about 10 c.c. of water, and 74 grams of salt. Stir 
thoroughly. Heat to boiling and fill boiling hot into small cans. Seal, 
store and examine as under Assignment X 3. 

Suggestions. The skins and seeds separated from the tomato pulp 
should be collected and weighed, after which this material should be 
dried at a moderate temperature in a dehydrater or over a radiator, 
weighed again and the skins separated from the seeds by fanning. The 
dry, clean seed should be retained for the preparation of tomato-seed 
oil as directed in Assignment XXVI. 



ASSIGNMENT XI. EXAMINATION OF COMMERCIAL 
FRUIT JUICES 

Materials. One bottle each of the juice of the following: Eastern 
grape, California grape, loganberry, pineapple, orange, apple and lemon. 
One can of pure apple juice and a sample of apple juice preserved with 
benzoate of soda. 

Procedure: 

1. Appearance. Before opening a bottle note whether the juice is 
brilliant, clear, hazy, cloudy or muddy ; whether there is a small, medium 
or large amount of sediment and whether this deposit is amorphous or 
crystalline. Describe the color of the juice. 

2. Net Contents. Determine the volume of juice in each container 
and report as fluid ounces. Compare with the net contents declared on 
the label. 

3. Flavor and Odor. Note the odor of the juice, especially in regard 
to the presence or absence of fresh-fruit aroma or of "cooked" odor. 
Note whether the flavor is fresh, stale or "cooked." Note whether the 
acid and sugar are agreeably balanced. Compare the flavor of apple 
juice containing benzoate of soda with that of juice free from this pre- 
servative. 

4. Balling Degree. Determine the Balling degree by means of a 
Balling hydrometer and record the temperature. Also determine the 
concentration by a Baume hydrometer and by an accurate specific- 
gravity hydrometer or Westphal balance. Convert Baume and specific- 
gravity readings to the corresponding Balling degree by means of Table 
XIV. Correct all readings for temperature by means of Table XIII. 

If desired, cane sugar and invert sugar may be determined by the 
methods given in the Appendix, page 100. 

5. Acid. By means of a pipette measure 10 c.c. of the sample into a 
500-c.c. flask. (With lemon juice dilute 10 c.c. to exactly 100 c.c., mix 
and take 10 c.c. of diluted juice for titration.) To light-colored juices 
add about 100 c.c. and to dark-colored juices about 300 c.c. of recently 
distilled water and a few drops of phenolphthalein indicator. Titrate as 
directed on page 98 of Appendix and express as grams of citric acid per 
100 c.c. of juice for citrus, pineapple and berry juices; as of tartaric acid 
for grape juice; and as of malic acid for apple juice. If the sample is 
carbonated, heat to boiling 10 c.c. of juice diluted with distilled water 
before titration. 

35 



36 LABORATORY MANUAL 

Suggestions: 

1. Compare the quality and the composition of the commercial juices 
with the fresh juices prepared in Assignment XIII. 

2. Carbonated beverages (bottled soda waters) prepared either from 
pure fruit juices, pure fruit syrups, or artificially flavored and colored 
syrups may be examined in a similar manner. The presence of sodium 
benzoate and coal-tar colors may be tested qualitatively as directed in 
the Appendix, page 102. The pressure of carbon dioxide may be deter- 
mined by shaking the unopened bottle vigorously and piercing the 
crown cap with a pressure gauge equipped with a sharp-pointed connec- 
tion, similar to a vacuum can-tester. 



ASSIGNMENT XII. EXPERIMENTAL PREPARATION OF 

FRUIT JUICES 

Materials. Fifty pounds of sound, ripe, tart apples or grapes. 

Procedure : 

1. Effect of Temperature of Pasteurization on Quality and on Pres- 
ence of Organisms. Extract the juice from the fruit as directed in As- 
signment XIII. To 800 c.c. of juice add several loopfuls each of active 
yeast and of ordinary green mold (Penicillium glaucum) spores. Mix 
thoroughly. Fill five 4- or 8-ounce bottles and seal with crown caps. 
Place one bottle in a horizontal position in a pot and cover completely 
with cold water. Place in the pot another bottle containing water into 
which is inserted a thermometer through a rubber stopper. Heat slowly 
until the thermometer registers 55C. Maintain this temperature 20 
minutes and remove the bottle of juice. In a similar way heat bottle 
No. 2 to 60C. for 20 minutes; No. 3 to 70C. for 20 minutes; No. 4 to 
80C. for 20 minutes; and No. 5 in boiling water for 20 minutes. Store 
all samples 4 weeks and examine for flavor and evidences of spoilage 
Repeat this series, using carbonated juice (see Assignment XII 2). 

2. Effect of Carbon Dioxide on Temperature of Pasteurization. If 
carbonating equipment is available, carbonate to 50 pounds gas-pressure 
enough juice, inoculated with yeast and mold as in Paragraph 1, to fill 
four bottles. Cap at once and heat one bottle at each of the tempera- 
tures used in Paragraph 1 for 20 minutes. Omit the boiling-water test. 
Store 4 weeks and compare with the samples from Assignment XII 1. 

If a carbonating machine is not available place about 1,000 c.c. of the 
juice in a large bottle and cool to about 0C. (32F.) by placing the 
bottle in crushed ice. Pass a slow stream of carbon dioxide from a Kipp 
generator or cylinder of carbon dioxide into the juice for 20 minutes, 
stirring occasionally. Bottle, cap and proceed as above. 

3. Caps as a Source of Mold. Wrap 5 crown caps in paper and heat 
in a steam sterilizer at 212F. for 1 hour. 

Fill ten 4-ounce bottles with juice and plug with cotton. Heat in a 
steam sterilizer for one hour at 212F. Allow to cool. 

Flame the necks of the bottles and cap five bottles with sterile caps, 
using every precaution possible against infection of the cork discs. Cap 
the remaining five bottles with untreated caps. 

Place the bottles in a pot of cold water and heat to 60C. (140F.) 

37 



38 LABORATORY MANUAL OF 

for 15 minutes. Store for 8 weeks and examine for evidence of mold 
growth. 

4. Bottles as a Source of Mold. Plug five 4-ounce bottles with cotton 
and sterilize one hour in a steam sterilizer at 212 F. Cool. 

Sterilize 1,500 c.c. of juice in a large bottle plugged with cotton at 
212F. in a steam sterilizer. Cool. Sterilize 10 caps as directed in 
Paragraph 3. 

Flame the necks of the sterile bottles and of the bottle of juice. Fill 
the five sterile bottles with sterile juice and seal with sterile caps. 

Fill five rinsed but not sterile bottles with sterile juice and seal with 
sterile caps. 

Pasteurize, store and examine as in Assignment XII 3. 

5. Effect of Temperature and Infusorial Earth on Filtration. Place 
100 c.c. of juice in a folded filter paper in a funnel and measure the 
volume of juice which filters through in five minutes. 

To 100 c.c. of juice add 3 grams of a finely ground infusorial earth, 
such as "Filter-eel." Mix thoroughly and determine the rate of filtration 
as above. Compare the clearness with that of untreated filtered juice. 

Heat 100 c.c of juice to 165 F. with 3 grams of Filter-eel and deter- 
mine the rate of filtration and clearness. Note effect, if any, of the 
Filter-eel on the flavor. 

6. Clarification with Finings. Allow 3,000 c.c. of fresh juice to stand 
overnight. Separate from the sediment by siphoning or decantation. 

A. Egg Albumen. Prepare 100 c.c. of a 2 per cent, solution of dried 
egg albumen in water by shaking the finely ground albumen in warm 
water (not above 110F.). To 100 c.c. portions of the settled juice in 
4-oz. bottles add enough of the albumen solution to be equivalent to 
additions of 0, 25, 50, 100 and 200 grams per hectoliter (100 liters) of 
juice. Cap the bottles and mix contents thoroughly by shaking. Heat 
to 165F. for 20 minutes. Shake and set aside for 24 hours. Note 
results. If any of the bottles are clear, decant off the clear juice, filter, 
bottle, and pasteurize at 165F. Store and compare later with untreated 
pasteurized juice for clearness and flavor. 

B. Casein. To 2 grams of casein add 2 c.c. concentrated ammonia 
and 50 c.c. of water. Boil until there is no longer any odor of ammonia. 
Dilute to 100 c.c. and use this casein solution to repeat clarifying tests 
as directed for egg albumen above. 

C. Spanish Clay. To 20 grams of finely ground Spanish clay in a 
mortar add 50 c.c. of water. Grind to a smooth paste. Add 50 c.c. more 
of water and repeat grinding. Dilute to 200 c.c. 

Repeat the clarifying tests as directed for egg albumen, but use the 
clay suspension at the rate of 200, 500, 1,000 and 1,500 grams (dry 
weight) of clay per hectoliter. The addition of one c.c. of the 10 per 



FRUIT AND VEGETABLE PRODUCTS 39 

cent, clay suspension per 100 c.c. of juice corresponds to 100 grams of 
clay per hectoliter. 

7. Comparison of Glass and Tin Containers. Fill one plain No. 2 
tin and one No. 2 lacquered can (completely) with juice, using berry or 
red grape juice if available. Heat in a water bath to 165F. and seal 
at once. Fill one No. 2 plain tin can and one bottle with the same juice 
and seal without heating. Pasteurize the cans and bottle of juice in 
water at 165F. for 30 minutes. Store one month and compare quality 
of juices and effects on container. 

8. Solubility of Metals in Fruit Juice. Weigh to one-tenth of a 
milligram clean dry pieces of iron, tin, aluminum, copper, zinc, silver, 
nickel and monel metal of approximately the same surface area. Place 
in individual beakers containing 100 c.c. of juice and boil slowly for 30 
minutes. Remove the metals, wash and dry thoroughly and weigh. 
Note the comparative losses in weight and calculate the loss in milli- 
grams per square centimeter. 



ASSIGNMENT XIII. PRACTICE IN THE PREPARATION 

OF FRUIT JUICES 

Materials. Five to ten pounds each of the following fruits in season: 
Apples, grapes, oranges, lemons, pomegranates, and loganberries or 
blackberries. 

Procedure : 

1. Preparation. Remove all unsound fruit and weigh. Wash thor- 
oughly. Cut citrus fruits in half. Separate the arals of pomegranates 
from the peel and "rag" and determine the yield of arals. 

2. Crushing. Crush thoroughly all fruits except citrus fruit. 

3. Heating. Heat crushed berries and red grapes in a jelly kettle 
or aluminum pot to 160F. with constant stirring. Other fruits are not 
heated before pressing. 

4. Extraction of Juice. Enclose the crushed fruits in heavy cloths 
and press in a small hand-press or under hydraulic pressure. Stir the 
pressed fruit and subject it to a second pressing. It is customary to 
place the crushed fruit in coarsely woven press-cloths between wooden 
racks and to subject it to a pressure of about 400 pounds per square inch 
for at least 30 minutes. 

Extract the pulp and juice from halved citrus fruits by means of a 
glass cone or a rotating bronze or aluminum cone. Strain the juice 
through cheese cloth to separate the coarse pulp. Measure the volume 
of juice obtained from each fruit and weigh the pomace. Determine the 
Balling degree and acidity of juice. 

From Table XIV obtain the corresponding specific gravity of the 
juice and calculate the yield of juice by weight. Calculate the yield of 
juice in percentage and in gallons per ton of fresh fruit. 

5. Clearing. Citrus juices should be bottled while cloudy. Other 
juices should be clear. 

Set the freshly expressed juice aside in a cool place for 24 hours. 
Separate from the sediment. Heat to 165F. Cool. Filter, using a 
small amount (1 to 3 per cent.) of infusorial earth if necessary. 

6. Bottling or Canning. Put the juice into clean bottles, filling to 
within about 1 inch of the top, and seal with crown caps. 

Fill one plain tin can with apple juice and one lacquered can with 
a red fruit juice. Exhaust to 165F. and seal. 

40 



41 




42 LABORATORY MANUAL 

7. Pasteurizing. Pasteurize 30 minutes at 165F. Chill cans in cold 
water. Store bottles in a cool, dark place. 

Suggestions: 

1. Utilization of Pomace. A. Jelly Stock: The pomace of fruits 
rich in pectin (such as apples, grapes and sour berries) may be utilized 
for jelly stock. To extract the pectin mix the pomace with about twice 
its weight of water and boil about ten minutes. Citrus fruits require 
40 minutes. Press out the extract and strain it through a jelly bag. 
Measure the volume obtained and determine its Balling degree and 
acidity. Pasteurize in lacquered cans or bottles for future use. 

B. Dried Pomace. The pomace may also be dried and the yield of 
dry material determined. The pectin of dried pomace from apples and 
other jelly fruits may be extracted for jelly making. 

C. Value for Syrup or Vinegar. From the yield and composition of 
the juice obtained in the preparation of jelly stock can be determined 
the value of the pomace as a source of syrup or vinegar. 



ASSIGNMENT XIV. PREPARATION OF FRUIT SYRUPS 

Materials. Apples or grapes, 100 pounds. Strawberries or other 
berries, 15 pounds. Samples of commercial fruit syrups. 

Procedure : 

1. Weigh the apples or grapes carefully and extract the juice as 
directed in Assignment XIII. Heat to 165F. and allow to settle. Filter. 
Determine the Balling degree, specific gravity and acid. 

2. Concentration in Vacua. Place a measured volume of the filtered 
juice in a small steam- jacketed vacuum pan. Concentrate rapidly to 
65 Balling, corrected to 20C. (68F.), using highest vacuum attain- 
able, preferably not less than 28 inches of mercury. Measure the volume 
of the syrup. 

Bottle or can in lacquered cans and pasteurize at 165F. for 30 
minutes. 

If a steam-jacketed vacuum pan is not available the juice may be 
concentrated in a heavy-walled flask immersed in a pot of water at 175 
to 180F. and connected through a water-cooled condenser to a vacuum 
pump. The flask should also be equipped with a vacuum gauge and 
thermometer. See Fig. 9. 

Note the temperature, vacuum and time required to concentrate the 
juice. 

3. Concentration in Open Pan. Place a measured volume of the 
filtered juice in a steam-jacketed kettle. Concentrate rapidly to 65 
Balling, corrected to 20C. (68F.). Record concentration and note time 
required. 

If a steam-jacketed kettle is not available concentrate the juice in an 
aluminum or agate-ware kettle over a flame. 

Pasteurize in bottles or in lacquered cans as directed in Assign- 
ment XIV 2. 

4. Concentration to Prevent Spoiling. Concentrate about 2,000 c.c. 
of juice to 75 Balling, corrected to 20C. (68F.). Dilute small por- 
tions to 70, 65 and 60 Balling, respectively. Place each sample in a 
bottle and add a loopful of yeast and mold spores to each. Cork the 
bottles and store for several weeks at room temperature. Examine to 
determine concentration necessary to prevent spoiling. 

5. Neutralized Syrup. Add to a measured quantity of filtered juice 
sufficient precipitated chalk (calcium carbonate) to reduce the acidity 
of the final syrup to 0.4 grs. per 100 c.c. The expected yield of syrup 
may be calculated from the data obtained in Assignment XIV 2 or by 

43 



44 



LABORATORY MANUAL OF 



formula No. 1 on page 45. The quantity of calcium carbonate required 
may be obtained by formula No. 2 on page 45. Boil the juice and calcium 
carbonate about one minute. Set aside overnight. Filter. Concentrate 
to 65 Balling, determine the yield and pasteurize as in Assignment XIV 2. 
6. Decolorized Syrup. To a measured quantity of juice add enough 
precipitated chalk (calcium carbonate) to neutralize the acid completely. 
Add 3 per cent, by weight of finely ground bone-black or 1 per cent, of 
Eponit, Noirit or other finely ground vegetable decolorizing carbon. Stir. 
Heat to boiling. Filter. Concentrate in vacua to 65 Balling; determine 
the yield and pasteurize as directed in Assignment XIV 2. 




FIG. 9. Sketch of laboratory apparatus for vacuum distillation. A, Boiling flask > 
B, Pot of water to heat boiling flask; C, Thermometer; D, Glass-condenser; E, 
Receiving bottle for distillate; F, Vacuum pump; G, Electric motor. 

7. Concentration by Freezing. Place a measured volume of the juice 
in a cold-storage room at to 10F. Allow to freeze to a mixture of 
ice crystals and syrup of "mushy" consistency. Place the partially frozen 
juice in a perforated centrifuge-basket and separate from the juice by 
centrifugal action. Repeat the freezing and centrifuging at least three 
times in order to obtain a concentrated juice of at least 50 Balling. 
Determine the yield and pasteurize as directed in Assignment XIV 2. 

If a freezing room and centrifuge are not available the juice may be 
frozen in an aluminum or agate-ware pot immersed in an ice-and-salt 
mixture or in an ice-cream freezer and the syrup separated from the ice 
crystals by draining through a fine screen or cheese cloth. 



FRUIT AND VEGETABLE-PRODUCTS 45 

8. Berry Syrup by Addition of Sugar. Prepare juice from a weighed 
amount of berries as in Assignment XIII. Allow to settle and filter. 
Determine the acidity and the Balling degree. Add sufficient sugar to 
increase the concentration to 65 Balling. Determine the yield. Pas- 
teurize as directed in Assignment XIV 2. 

9. Comparison of Samples. Store all prepared samples for four weeks 
or longer. Compare carefully with respect to flavor, color, odor, acidity 
and general quality. Also compare the experimentally prepared syrups 
with commercial syrups if obtainable. Determine the Balling degree and 
acidity of commercial samples. 

Suggestions: 

1. Formula for Calculating Yield of Syrup: 

sXbXlOO 
SXB 

G = yield of syrup from 100 parts of juice by volume 
s = specific gravity of juice 
S = specific gravity of syrup 
b== Balling degree of juice 
B = Balling degree of syrup 

2. Formula for Reducing Acidity of Syrup by Neutralization of Acid 
in Juice Before Concentration: 

* 



S N 

J =c.c. juice used 
A = gms. acid per 100 c.c. juice 
S = c.c. syrup obtained 

R = gms. acid to be retained per 100 c.c. syrup 
N = gms. acid neutralized by 100 gms. calcium carbonate 
C = gms. calcium carbonate required 

Theoretically 100 gms. calcium carbonate (CaCO 3 ) will neutralize 
134 gms. malic acid (C 4 H O 5 ) in apple juice or 150 gms. tartaric acid 
(C 4 H 6 O C ) in grape juice. 

3. Determination of Acidity of Syrups. On account of the viscosity 
of most syrups it is necessary to weigh a sample of the syrup (10 grams) 
for titration, rather than to measure the volume of the sample by means 
of a pipette. 

4. Determination of Balling Degree of Syrups. If syrup is very 
viscous it is necessary to mix 100 grams (not 100 c.c.) of the syrup with 
100 c.c. of distilled water before making the Balling test. The reading 
thus obtained must be multiplied by 2. 



ASSIGNMENT XV. EXAMINATION OF COMMERCIAL 
JELLIES, JAMS, MARMALADES AND PRESERVES 

Materials. Samples of the above products. 

Procedure : 

1. Determine the net contents of the containers by weight. 

2. Note the appearance, color, flavor, odor and clearness of each 
syrup or jelly. The samples should be examined carefully for evidence 
of mold growth and of fermentation. 

3. Determine the Balling degree and total acid of the syrup from 
each preserve as directed in Assignment XIV. Place a 50-gram sample 
of jelly or marmalade in a weighed 400-c.c. beaker. Add exactly 100 
c.c. of water. Heat and stir until dissolved. If necessary add water to 
replace that lost during heating. Cool and determine the Balling degree 
and acid. Multiply the results by three. 

4. Microscopical Examination. Mount small samples of the prod- 
ucts on a microscope slide. Very concentrated products and jams should 
be diluted on the slide with a drop of distilled water. The presence of 
large numbers of micro-organisms, especially mold filaments or yeast 
cells, indicate the use of partially decomposed raw material. 

5. Artificial Color and Benzoate of Soda. The presence of artificial 
color or sodium benzoate may be determined qualitatively by the 
methods given in the Appendix, page 102. 

Suggestions: 

1. Definitions A. Jelly. Jelly is prepared by boiling fruit with or 
without water, expressing and straining the juice, adding sugar (sucrose) 
and concentrating to such consistency that gelatinization takes place on 
cooling. A perfect jelly is clear, sparkling, transparent and attractive 
in color. When removed from the glass it should retain its form and 
should quiver, not flow. It should not be syrupy, sticky or gummy and 
should retain the flavor and aroma of the original fruit. When cut it 
should be tender and yet so firm that a sharp edge and a smooth sparkling 
cut-surface remain. 

B. Marmalade. True marmalade is clear jelly in which is suspended 
slices of fruit or peel. 

C. Jam. Jam is prepared by boiling the whole fruit pulp with sugar 
(sucrose) without retaining the shape of the fruit. It is concentrated 
to a thick consistency without straining. Government pure-food regula- 

46 



47 

tions require the use of not less than 45 pounds of fruit to each 55 pounds 
of sugar. 

D. Butter. Fruit butter is prepared by boiling the strained fruit 
pulp, with or without the addition of sugar, fruit juice or spices, to a 
semi-solid mass of homogeneous consistency. It differs from jam in 
being of a finer texture and a higher concentration. 

E. Paste. Fruit paste is prepared as described for fruit butter, but 
is concentrated to a semi-solid consistency by boiling and is then dried 
to a solid consistency resembling candy. 

F. Preserves. Preserves are made by cooking the prepared fruit in 
a sugar (sucrose) syrup until the concentration of sugar reaches 55 to 70 
per cent. The fruit should retain its form, be crisp rather than soft, and 
should be permeated with the syrup. Government pure-food regulations 
require that not less than 45 pounds of fruit be used for each 55 pounds 
of sugar. 



ASSIGNMENT XVI. EXPERIMENTAL PREPARATION OF 
JELLY AND MARMALADE 

Materials. Sour apples 15 pounds, oranges 5 pounds, and lemons 
5 pounds. 

Procedure : 

1. Preparation. Prepare jelly stock from a weighed amount of sour 
apples (about 15 pounds), as directed in Assignment XVII. Test quali- 
tatively for pectin content as directed in Assignment XVII. If the juice 
is not rich in pectin, concentrate by boiling until a heavy pectin precipi- 
tate is obtained by the alcohol test. Record the yield, acidity and Ball- 
ing degree. 

2. Effect of Pectin Concentration. A. Dissolve 185 grams of sugar 
in 100 c.c. of the prepared juice. Heat to boiling for one minute. Skim 
and pour into a glass. 

B. To 50 c.c. of the juice add 50 c.c. of water. Add 185 grams of 
sugar and treat as in A. 

C. To 25 c.c. of the juice add 75 c.c. of water, 185 grams of sugar 
and proceed as in A. 

Compare consistencies of the samples after 48 hours. 

3. Effect of Acidity. A. If the acidity of the juice is less than 1 per 
cent., increase the acidity of 100 c.c. to 1 per cent, by the addition of 
citric acid. Add 185 grams of sugar, dissolve, and heat to boiling for one 
minute. Skim and pour into a glass. 

B. Repeat A, increasing the acidity to 2 per cent. 

C. Repeat A, increasing the acidity to 5 per cent. 

D. Reduce the acidity of 100 c.c. of juice to 0.2 per cent, by the 
addition of the calculated amount of sodium carbonate (Na 2 CO 3 ). One 
gram of Na 2 C0 3 will neutralize 1.21 grams citric and 1.26 grams malic 
acid. Add 185 grams of sugar, boil one minute; skim and pour into 
a glass. 

Compare the consistencies and flavors of samples after 48 hours. 

4. Effect of Sugar Concentration. To 100 c.c. portions of the juice 
add 50, 150, 200 and 300 grams of sugar, respectively. Dissolve the 
sugar, boil each sample one minute, skim and pour into glasses. 

Compare the consistencies and flavors after 48 hours. Note the 
presence or absence of sugar crystals. 

48 



FRUIT AND VEGETABLE PRODUCTS 49 

5. Effect of Temperature. Dissolve in each of three 100-c.c. portions 
of juice 185 grams of sugar. Heat one lot to boiling one minute, the 
second lot to 165F. one minute, and the third lot in an autoclave at 
10 pounds steam pressure (240F.) five minutes. 

Compare for color, flavor and consistency after 48 hours. 

6. Comparison of Jelling-point Tests. To each of four 100-c.c. lots 
of the juice add 100 grams of sugar. Boil in an open pot with a ther- 
mometer inserted in the boiling liquid. Remove lot 1 when the heating 
point reaches 216F.; lot 2 at 218F.; lot 3 at 221F., and lot 4 at 
225F. Also allow some of the hot liquid to drip from a spoon and note 
whether the drops congeal or not, and determine the Balling degree of 
each lot as soon as removed from the fire (making the necessary tem- 
perature corrections). 

Compare the flavors, colors and textures after 48 hours. 

7. Jelly from Dried Apple Waste. To 100 grams of dried peels and 
cores of apples (canning refuse) or of dried pomace from apple-juice 
manufacture add 500 c.c. of water. Bring to the boiling point and set 
aside overnight. Boil about 20 minutes, press and filter. 

Test for pectin and if necessary concentrate until a fairly heavy test 
is given. 

Add an equal quantity of berry juice, such as strawberry juice or 
commercial grape juice, and sugar in the proportion of 75 grams per 
100 c.c. of mixed juice and concentrate to a boiling point of 221 F. 
Pour into glasses and store for subsequent examination. 

8. Citrus Fruit Marmalade A. Preparation. Prepare jelly stock 
from a weighed amount of citrus fruit, about 5 pounds each of oranges 
and lemons, as directed in Assignment XVII. Test qualitatively for 
pectin content and, if a heavy test is not secured, concentrate by boiling. 
Record the yield, acidity and Balling degree. 

B. Effect of Preliminary Boiling of Peel. To 200 c.c. of the juice 
add 30 grams of shredded peel and 150 grams of sugar. Boil until a 
thermometer in the liquid registers 221 F. and pour into a glass. 

To 30 grams of the shredded peel add about 300 c.c. of water. Boil 
until the shreds are tender. Drain off and discard the water. To the 
drained peel add 200 c.c. of juice and 150 grams of sugar. Heat to 
221 F. Pour into a glass. 

Compare the texture of the peel in the two lots after 48 hours. 
Measure the yield of finished product. 

C. Effect of Cooling before Pouring. Prepare a sample of marma- 
lade as directed in B, using the boiled peel, but allow the product to cool 
in the pot with occasional stirring until it shows slight signs of jelling. 
Pour it into a glass and after cooling note whether the shreds are more 
evenly distributed in the product than in B. 



50 LABORATORY MANUAL 

D. Effect of Proportion of Peel. To 100-c.c. lots of the juice add 
5, 10, 20 and 30 grams, respectively, of thinly sliced boiled peel and 100 
grams of sugar. Concentrate each lot until a boiling point of 221 F. 
is reached. Pour into glasses. Compare as to texture, appearance and 
general quality after 48 hours. 



ASSIGNMENT XVII. PRACTICE IN THE PREPARATION 
OF JELLY AND MARMALADE 

Materials. Any fruit in season suitable for jelly making. 

Procedure : 

1. Condition of Fruit. Fruit for jelly should be sound and clean and 
not thoroughly ripe, as under-ripe fruit is richest both in pectin and 
in acid. 

2. Extraction of Pectin. The pectin must be released from the fruit 
tissues by boiling. Very juicy fruits such as berries are merely crushed 
and boiled about 5 minutes without the addition of water. Hard fruits 
such as quinces or apples are cut into small pieces, barely covered with 
water and boiled 10 or 15 minutes till tender. Citrus fruits are sliced 
without peeling into thin pieces, covered with water and boiled about 
one hour. 

3. Pressing and Clearing. With large quantities, the boiled fruit is 
pressed as described under Fruit Juices. The juice is allowed to settle 
overnight and the settled juice filtered through a felt jelly-bag. Small 
quantities of boiled fruit are generally placed directly in a muslin jelly- 
bag and the clear juice allowed to drain through. The last of the juice 
may be squeezed out, but it will be cloudy. The drained or pressed 
pulp of fruits rich in pectin may be boiled a second time with water 
and drained or pressed. 

4. Orange Peel for Marmalade. If equal quantities of oranges and 
lemons are used for the marmalade stock, only one orange in four need 
be peeled. Remove the orange peeling by quarters and cut into very thin 
slices, not more than 1/32 of an inch thick. Boil the sliced peel in water 
until tender. Drain and discard the water. 

5. Testing for Pectin. Mix in a glass equal quantities of juice and 
95 per cent, grain alcohol. One spoonful or about 10 c.c. of each is 
sufficient. The character and amount of precipitate indicate the relative 
concentration of pectin as follows: 

Juice rich in pectin = bulky, gelatinous, almost solid mass of pectin. 
Juice moderately rich in pectin = a few large pieces of gelatinous 
precipitate. 

Juice poor in pectin =. small amount of flaky sediment. 

6. Testing for Acid. The acidity of the jelly stock may be deter- 
mined as described on page 98. An acid content of 0.5 to 1.0 per cent. 

51 



52 



LABORATORY MANUAL OF 




FRUIT AND VEGETABLE PRODUCTS 53 

is satisfactory. Juices with a distinctly tart taste need not be tested 
for acid. 

7. Proportion of Sugar and Juice. The amount of sugar which may 
be added to the juice is directly proportional to the concentration of 
pectin in the juice, as follows: 

To one cup of juice rich in pectin add 1 to l 1 /^ cups of sugar. 
To one cup of juice moderately rich in pectin add % to 1 cup of sugar. 
To one cup of juice fairly rich in pectin add y> to % cup of sugar. 
Juices poor in pectin should be concentrated until a satisfactory 
pectin test is obtained before addition of sugar. 

8. Determination of Jelling Point. The proper proportion of sugar 
and juice is boiled rapidly until the mixture reaches a concentration of 
65 to 68 Balling (cold test). The jelling point may be determined in 
the following ways, the thermometer test being the simplest and most 
reliable : 

A. Sheeting Test. Dip a spoon or paddle in the boiling jelly. Hold 
the spoon in the air and allow the jelly to drip from it. If the drops are 
syrupy the jelly is not sufficiently concentrated, but if the jelly congeals 
or drops in flakes the jelling point has been reached. 

B. Boiling-point Test. Place a thermometer in the jelly during con- 
centration. When the jelly boils at 221 F., equivalent to 65 Balling, 
the jelling point is reached. 

C. Balling Test. Pour a sample of the boiling jelly in a hydrometer 
cylinder and determine Balling degree. At the jelling point the Balling 
degree of the hot jelly should be 57 to 58, equal to 65 when cold. 

9. Sealing, Pasteurizing and Storage. The hot finished jelly, 
skimmed to insure clearness, is poured into glasses and allowed to cool 
and solidify. The surface of the jelly is then covered with a layer of 
hot melted paraffine, which sterilizes the surface of the jelly and solidi- 
fies to form a seal about % inch thick. 

Jelly may also be sealed in small fruit-jars with caps and rubber 
gaskets or in lacquered cans. This is necessary where the jelly is to be 
pasteurized at 180F. for 30 minutes in the case of soft jellies that are 
below 65 Balling, and especially if to .be kept in hot climates. 



54 



LABORATORY MANUAL 



Suggestions: 

1. Suitability of Fruits for Jelly: 



Rich in Pectin and 


Medium in Acid and 


Rich in Pectin and 


Poor in Acid and 


Acid 


Pectin 


Low in Acid 


Pectin 


Jell readily 


Jell if carefully handled 


Add acid fruit 


Blend with fruit 
from Column 1 


Sour apples 


Ripe apples 


Guavas 


Apricots 


Crab apples 


Blackberries 


Feijoas 


Peaches 


Currants 


Oranges 


Figs 


Pears 


Loganberries 


Grape Fruit 


Pie melons 


Raspberries 


Cranberries 


Sweet plums 




Strawberries 


Lemons 


Quinces 






Sour plums 


Sour cherries 






Eastern grapes 


California grapes 







2. Common Difficulties in Jelly-making, with Cause or Prevention. 

A. Soft or Syrupy Jelly. Too much sugar for amount of pectin or 
insufficient boiling; add more juice or pectin and heat to 221 F. 

B. Tough Jelly. Too little sugar for amount of pectin; add more 
sugar. 

C. Gummy Jelly. Too prolonged boiling or over-cooking; boil rap- 
idly and stop at 221 F. 

D. Cloudy Jelly. Juice not strained; jelly not skimmed or partly 
congealed before filling into glasses; use clear juice, skim jelly and pour 
hot into glasses. 

E. Crystals. Sugar crystals due to lack of thorough stirring and 
dissolving or too much sugar added or jelly too concentrated. In grape 
jelly the harmless cream of tartar crystals may occur. 

F. Moldy Jelly. Paraffine not hot when poured or caps not steri- 
lized or seal not tight. Use thicker layer of hot melted paraffine or 
sterilized covers. 

G. Fermented Jelly. Not concentrated to 65 Balling. Add more 
sugar, heat to 221F., or pasteurize in sealed jars. 



ASSIGNMENT XVIIL -EXPERIMENTAL PREPARATION 
OF PECTIN AND JELLY STOCK 

Materials. Apples 10 pounds, or oranges and lemons 5 pounds each. 
Cull fruits may be used. Commercial powdered pectin and concentrated 
pectin solution. 

Procedure : 

1. Preparation of Juice. Prepare jelly stock from apples or equal 
weights of lemons and oranges as directed in Assignment XVII. Test 
qualitatively for pectin content. If the juice is not rich in pectin, con- 
centrate by boiling. Determine the yield, acidity and Balling degree. 

2. Canned Jelly Stock. To 100 c.c. of the juice add 100 grams of 
sugar and concentrate to a boiling point of 221 F. Pour into a glass, 
seal and store for future reference. 

Fill to overflowing with the boiling juice one lacquered can and one 
plain tin can. Seal at once and invert to cool. Store at least one month. 
Open cans and note action of juice on containers. Prepare jelly from 
each sample as directed above and compare the quality with that of 
jelly made from the fresh fruit. 

3. Preparation and Use of Concentrated Pectin Solution. Determine 
the acidity and Balling degree of a sample of commercial concentrated 
pectin solution. Concentrate in vacuo 500 c.c. of the jelly stock to the 
same Balling degree as the commercial pectin solution. Compare the 
pectin content of each of the two products qualitatively after diluting 
one part of the sample with four parts of water. 

Pasteurize the concentrated pectin solution in a bottle at 175F. for 
30 minutes. Store 1 month. Dilute part of the sample to the concen- 
tration of the original juice. To 100 c.c. of the diluted solution add 
100 grams of sugar and heat to 221 F. Compare witli the jellies made 
from canned jelly stock and fresh juice in Assignment XVIII 2. 

To 100 c.c. of strawberry juice, or other juice poor in pectin, add 
enough of the concentrated pectin solution to give a strong pectin test 
and record the amount used. Prepare jelly as directed above. For 
comparison add to 100 c.c. of the juice poor in pectin enough concen- 
trated commercial pectin solution to give a strong pectin test and prepare 
jelly from the mixture. Compare amounts of the two pectin solutions 
required to give similar qualitative pectin tests and compare the jellies 
obtained as to quality. 

55 



56 LABORATORY MANUAL 

4. Preparation of Powdered Pectin. Concentrate 1,000 c.c. of the 
jelly stock in vacuo to about 45 to 50 Balling. Cool, and add the 
concentrated juice slowly with stirring to twice its volume of 95 per cent, 
ethyl (grain) alcohol. Separate the alcohol from the pectin by draining 
through a muslin cloth and pressing. Dry at room temperature on a 
screen. Dissolve the dried pectin in a small amount (about 150 c.c.) 
of water and strain through a cloth. Add the pectin solution to twice 
its volume of ethyl alcohol and separate the precipitate by straining 
through muslin. Dry at a temperature of 120 to 130F. and weigh. 
Grind in a mortar to a powder. Store in a corked bottle. 

Dissolve 0.5, 1 and 2 grams, respectively, in 100-c.c. lots of juice 
poor in pectin. Add 100 grams of sugar to each. Concentrate by boiling 
to 221 F. Pour into glasses and compare the samples 48 hours later as 
to consistency. 

Suggestions. The alcoholic liquid from the pectin precipitation 
may be distilled to recover the alcohol, the alcohol content of the dis- 
tillate determined and the loss of alcohol ascertained. 



ASSIGNMENT XIX. PRACTICE IN THE PREPARATION 
OF JAM, BUTTER AND PASTE 

Materials. Apples 10 pounds, peaches or apricots 5 pounds, berries 
5 pounds and pears 5 pounds. Fruits for the products above mentioned 
should be thoroughly ripe. 

Procedure : 

1. Jams A. Preparation. Weigh and wash the fruit thoroughly. 
Do not use apples. Peel and slice peaches and pears. Pit and slice 
apricots. Wash and stem berries. Firm fruits such as pears should be 
boiled until soft with a small amount of water before adding sugar. 

B. Addition of Sugar. To sour fruits add an equal weight and to 
sweet fruits three-fourths their weight of sugar. 

C. Concentration. Heat with constant stirring to a boiling point of 
218 to 221 F., or until the desired consistency is reached. Seal while 
boiling hot in jars or glasses. Record the yield. 

2. Butters A. Preparation of Pulp. Weigh, peel and slice apples, 
pears or peaches. Boil with a small amount of water until soft. Pass 
through a fine screen. 

B. Addition of Sugar or Fruit Juice. Butters are made either with 
sugar or fruit juice added to pulp. If the former is used, add three- 
fourths pound of sugar per pound of pulp; if the latter, add 3 pints of 
apple juice or grape juice per pound of pulp. 

C. Addition of Spices. Cinnamon and cloves are usually added in 
the proportion of one level teaspoonful of each of the ground spices per 
3 pounds of pulp or one gram of each per 1,000 grams of pulp. These 
are added near the completion of the boiling process. 

D. Lemon juice is added to pear pulp in the proportion of three- 
fourths of a pint per 10 pounds of pulp or 50 c.c. per 1,000 grams of pulp. 

E. Concentration. Concentrate the pulp and sugar or juice to a 
very thick consistency (222 to 225F.). Determine the yield and seal 
while hot in fruit jars or cans. 

3. Paste. Use pears, peaches, apricots or berries. Prepare the fresh 
fruit as described for butters. Add to the screened pulp three- fourths 
its weight of sugar. Concentrate to a boiling point of 222F. Spread 
in a layer about l / 2 inch thick in a buttered or greased pan. Dry to a 
solid consistency at 120 to 160F. in an air-blast dehydrater or in a 

57 



58 LABORATORY MANUAL 

glass-covered dish in the sun. Cool. Cut into square blocks. Dip in 
powdered sugar and determine the yield. 

Suggestions. Commercial pectin or apple juice rich in pectin is 
often added to fruit jam to thicken its consistency or to cheapen the 
product. 



ASSIGNMENT XX. EXPERIMENTAL PREPARATION OF 
FRUIT PRESERVES 

Materials. Strawberries 5 pounds, and cherries, oranges or slightly 
unripe figs 3 pounds. If fresh strawberries are not in season it is usually 
possible to obtain cold-storage strawberries. 

Procedure: 

1. Effect of Preliminary Cooking. Use fresh whole figs or the white 
flesh of watermelon cut in small cubes, or orange peel cut in quarters. 

A. To 1 pound (454 grams) of the fruit, add 1 pound. (454 grams) 
of sugar and % pint (about 240 c.c.) of water, boil to 221 F. and allow 
to cool. 

B. To 1 pound (454 grams) of the fresh fruit, add 2 pints (about 950 
c.c.) of water and boil until tender. This will be 45 to 50 minutes for 
orange peel and 20 to 25 minutes for figs or melon. Discard the water. 
To the cooked fruit add 1 pound (454 grams) of sugar and % pint (about 
240 c.c.) of water. Heat slowly to 221 F. Allow to cool and compare 
the texture with that of sample A. 

2. Effect of Method of C-oncentration. A. Place 1 pound of hulled 
washed strawberries in an open kettle. Add 1 pound of sugar. Heat to 
221 F. and allow to cool. 

B. Place equal weights of berries and sugar in a large flask connected 
to a condenser and vacuum pump. Place the flask in water at 185F. 
and concentrate under at least 26 inches vacuum until the syrup tests 
65 Balling (corrected for temperature). Allow to cool and compare 
with A and C. 

C. To 1 pound of berries add 1 pound of sugar. Heat slowly to boil- 
ing. Boil 3 minutes. Allow to stand with occasional stirring for about 
12 hours to permit the berries to absorb the syrup. Heat to 185F., 
pack hot into a jar; seal; pasteurize 20 minutes at 185F. and invert 
to cool. Compare with A and B. 

D. To 1 pound of berries add 1 pound of sugar. Boil 3 minutes and 
place in a shallow dish in the sun or in a dehydrater at 120F. until 
syrup reaches 65 Balling. Compare witli A, B and C. 

Suggestions. If fresh fruits are not in season dried figs, peaches 
or pears may be soaked in water and used for this assignment. 



59 



ASSIGNMENT XXL PRACTICE IN THE PREPARATION 
OF FRUIT PRESERVES 

Materials. Five pounds each of such fruits as peaches, pears, straw- 
berries, pineapple, watermelon rind, kumquats, cherries, apricots and 
firm ripe figs. 

Procedure : 

1. Preparation. Weigh the fruit before and after preparation as 
follows: 

A. Freestone peaches peel, halve, pit. 

B. Cling-stone peaches peel, but need not pit. 

C. Small pears peel and use whole. 

D. Large pears peel, halve, core. 

E. Quinces peel, quarter and core. 

F. Cherries stem and pit. 

G. Apricots halve and pit. 

H. Small plums puncture skins thoroughly. 

7. Kumquats slit and seed. 

J. Pineapple peel, core and slice. 

K. Watermelon remove red flesh and green skin. 

2. Preliminary Boiling. Boil watermelon rind and fruits, such as 
figs, peaches, pears, kumquats and cherries, in water until tender. Do 
not boil soft fruits, such as berries and very ripe apricots or free-stone 
peaches. 

3. Addition of Sugar. To each pound of firm varieties of fruit add 
1 pound of sugar and 1 quart of water. To berries and very ripe soft 
fruit add sugar only. Heat firm fruits in an open kettle to a temperature 
of 221 F. ; boil berries with gentle stirring 3 to 4 minutes only. Allow 
to cool in an open vessel, stirring frequently during cooling. Set aside 
for 24 hours to allow the fruit to absorb the syrup. 

4. Packing and Pasteurizing. Pack the fruit carefully into glass 
jars. Heat the syrup from the fruit to boiling and fill the jars. Seal 
the jars and pasteurize for 30 minutes in water at 185F. 

5. Spiced Preserves. Prepare firm fruits as directed in Assignment 
XXI 1 and 2. Berries are not suitable for spiced preserves. Prepare a 
syrup consisting of: 

60 



FRUIT AND VEGETABLE PRODUCTS 61 

Sugar 1,400 grams 

Vinegar 475 c.c. 

Water 475 c.c. 

Ginger root 7 grams 

Whole cloves 10 grams 

Stick cinnamon 15 grams 

Heat the fruit to boiling in this syrup and allow to stand overnight. 
Add sugar sufficient to increase the Balling degree of the syrup to 60. 
Heat the fruit and syrup to boiling. Pack hot into jars and seal. No 
further treatment is necessary. 

6. Maraschino Cherries. Store large Royal Anne cherries for at least 
two weeks in sealed glass-top fruit-jars in a 0.3 per cent, solution of 
sulphurous acid or in a 0.5 per cent, solution of sodium metabisulphite. 

Stem and pit the cherries. Allow to stand in water overnight. Boil 
in repeated changes of water until the fruit is tender and free of sul- 
phurous acid taste. 

Prepare a syrup of 30 Balling with confectioners' gluecose or white 
"Karo" syrup and water. Color the syrup to the desired depth and tint 
by the addition of small amounts of the permissible coal-tar dyes, 
Amaranth and Ponceau-3-R. Heat the fruit to boiling in this syrup 
and set aside for 24 hours. Increase the Balling degree progressively 
at 24-hour intervals to 35, 40, 45, 50 and 55 Balling by addition of 
cane-sugar, boiling the fruit and syrup for about three minutes after 
each increase. Add a very small amount of bitter-almond or "wild 
cherry" extract to the syrup of 55 Balling, heat to boiling and pack 
into glass-jars or lacquered-cans. Seal and sterilize the cans in boiling 
water for 10 minutes and the jars in water at 185F. for 20 minutes. 
A more attractive product is obtained if the cherries are packed in 
freshly prepared cane-sugar syrup of 55 Balling flavored with bitter- 
almond oil. 



ASSIGNMENT XXII. PRACTICE IN THE PREPARATION 
OF CANDIED FRUITS 

Materials. Apricots, cherries, figs, jujubes, oranges, kumquats, 
small Seckel pears or canning peaches. Most fruits for candying should 
be hard ripe. 

Procedure: 

1. Preliminary Treatment. Take a weighed quantity of the fruit. 
Jujubes are first dipped in boiling 1 per cent, sodium hydroxide (NaOH) 
solution for about ^ minute and rinsed in water to remove the waxy 
coating on the skin and to render the skin permeable to the syrup. Some 
whole fruits such as apricots should be punctured thoroughly with a fork. 
Cherries are pitted and stemmed. Peaches are peeled, pitted and halved. 
The pits are removed from large apricots without cutting in half. Use 
only the peel of oranges. The skins of kumquats are cut longitudinally 
and the seeds are removed. 

Cook the fruit in water until tender, but not "mushy." 

2. Impregnation with Syrup. Prepare a glucose syrup of 30 Balling 
from glucose syrup and water. Place the fruit in this and heat to boiling. 
Set aside for 24 to 48 hours. 

Pour off the syrup. Add cane-sugar to increase to 40 Balling. Place 
the fruit in the syrup. Heat to boiling. Set aside for 48 hours. 

Increase tlie syrup progressively at 48-hour intervals to 50, 60 and 
70 Balling by the addition of cane-sugar. Heat the syrup and fruit 
to boiling after each increase. 

The syrup used for cherries must be artificially colored to give the 
tint commonly seen in candied cherries. Equal proportions of the per- 
missible aniline colors Ponceau-3-R and Amaranth are used. These are 
added when the first syrup is prepared. Bitter-almond flavor is added 
to the final syrup for cherries. 

3. Drying and "Glaceing." Remove the fruit from the heavy syrup. 
Drain well on screen trays. Dry the surface of the fruit at not over 
130F. Weigh. Part of this fruit may be packed in boxes without 
further treatment. Reserve the remainder for glaceing. 

Prepare a concentrated sugar-solution containing 60 grams of sugar 
and 25 grams of glucose-syrup per 15 c.c. of water. Boil and allow to 
cool to about 200F. Dip the remainder of the fruit in this very heavy 
syrup. Drain and dry in the open air at not above 110F. 

62 



FRUIT AND VEGETABLE PRODUCTS 63 

Weigh the finished product. Compare the appearance of the glace 
and plain samples. 

Suggestions : 

1. If fresh fruits are unavailable, canned fruits may be substituted. 

2. Apples, berries and very ripe fruits of any kind are unsuitable for 
candying because they disintegrate during processing. 

3. Cherries are usually prepared for candying as described in Assign- 
ment XXI-6. 



ASSIGNMENT XXIII. EXAMINATION OF COMMERCIAL 
DRIED FRUITS AND VEGETABLES 

Materials. Samples of various size-grades of sun-dried fruits, such 
as peaches, pears, apricots, prunes and raisins. Samples of dehydrated 
fruits, such as prunes, apples, berries, peaches, pears, etc. Samples of de- 
hydrated vegetables, such as spinach, corn, string beans, soup vegetables 
and of pumpkin flour. 

Procedure : 

1. General Examination. A. Appearance. Note the shade and uni- 
formity of color, comparing with the natural color of the fresh product. 
In dried whole fruits, note the appearance of the interior of each. Note 
differences in color between sun-dried and dehydrated fruits. Examine 
carefully for dust, dirt, straw and evidence of carelessness in peeling 
or washing. 

B. Flavor. Note the flavor of each kind of fruit. Taste for evidence 
of sulphurous acid or caramelization of sugar. 

C. Evidence of Spoiling. Examine for evidences of insect infestation. 
The common insects which may be found in dried fruits or vegetables 
are, in order of their importance: 

(a) Indian-Meal Moth (Plodia interpunctella). 
(6) Dried-Fruit Beetle (Carpophilus hemipterus). 

(c) Grain Beetle (Silvanus surinamensis). 

(d) Dried-Fruit Mite (Carpoglyphus passularum). 
Examine for evidence of micro-biological decomposition, namely, 

mold, alcoholic fermentation or bacterial growth. A small portion of 
the sample may be ground with a little water in a mortar and a drop 
of the mixture placed on a glass slide and examined under the high power 
of the microscope. Do not confuse efflorescence of sugar on the surface 
of fruits with white mold. 

2. Grades. Determine the size grades of dried fruits by reference 
to Table X. 

3. Chemical Examination. A. Determination of Moisture. Grind a 
representative sample of not less than 1 pound of fruit, free from pits, 
or ^2 pound of vegetable, through a fine food-chopper. Determine the 
moisture by the official method as given on page 102. Moisture in dried 
apples may be determined by drying 10 gramss of the minced sample in a 

64 



FRUIT AND VEGETABLE PRODUCTS 65 

water-oven for exactly 4 hours at not less than 96C. This method does 
not apply to other fruits. The legal limit for moisture in dried apples 
is 24 per cent. Legal limits for moisture in other dried fruits and vege- 
tables have not been adopted. 

B. Sugar in dried fruits may be determined as outlined on page . 

C. Sulphurous acid in sulphured fruits may be determined as out- 
lined on page 100. 

4. Refreshing Test. A. Place an accurately weighed amount of dried 
fruit or vegetable ( l /2 pound or less) in a pot and cover with boiling 
water and allow to stand 12 to 24 hours. 

B. Drain on a piece of screen of %-inch mesh and record the 
increased weight of the product. 

C. Return the drained product to the liquid and boil gently until 
tender, adding sugar, salt or spices to taste. 

D. Note the color, odor and flavor of the cooked product. 

Suggestions : 

1. A brief description of the standard grades of California dried fruits 
is given in Table X. 

TABLE X. GRADES OP CALIFORNIA DRIED FRUITS 

APPLES, Evaporated (Artifically dried): 

Extra Fancy. Fairly uniform size rings; uniform white color; clean; free from skins, 
cores, stems, bruised or rotten spots, worm holes or screening. 

Fancy. Fairly uniform size rings; uniform white or very light yellow color; clean; 
almost free from skins, cores, stems, bruised or rotten spots, worm holes or screenings. 

Extra Choice. Rings of fairly uniform white or light yellow color; not more than 
25 per cent of pieces showing skins, cores, stems, bruised or rotten spots or worm holes; 
fairly free from screenings. 

Choice. Rings of white, yellow or light brown color; not more than 50 per cent of 
pieces showing skins, cores, stems, bruised or rotten spots, worm holes; may contain 
noticeable amount of screenings. 

Standard. Brown color; large percentage of pieces showing skins, cores, stems, 
bruised or rotten spots and of screenings. 

APRICOTS, California Sun Dried: 

Size Grades. Extra Fancy, over 48/32 inches diameter. 
Fancy 48/32 inches diameter. 

Extra Choice, 40/32 inches diameter. 
Choice, 32/32 inches diameter. 

Standard, below 32/32 inches diameter. 

Quality Grades. Dried apricots are sold according to variety and locality, Blenheims 
and Moorparks predominating in the Santa Clara Valley and the Royal in the Sacra- 
mento and San Joaquin Valleys and southern California. Two general quality grades 
are recognized: 

First. Bright colored, well bleached, meaty, clean, neatly cut halves. 

Second. Darker, not so well bleached, thinner, or ragged edges. 



66 LABORATORY MANUAL OF 

FIGS, California Sun Dried: 
Black Figs (Mission Variety): 

Fancy, over 34/32 inches diameter. 

Choice, 34/32 inches diameter. 

Standard, 28/32 niches diameter. 

White Figs (Calimyrna and Adriatic Varieties): 
Fancy, over 42/32 inches diameter. 
Choice, 42/32 inches diameter. 
Standard, 34/32 inches diameter. 

PEACHES, California Sun Dried: 

Size Grades. Extra Fancy, over 58/32 inches diameter. 

Fancy, 58/32 inches diameter. 

Extra Choice, 50/32 inches diameter. 

Choice, 42/32 inches diameter. 

Standard, 34/32 inches diameter. 

Classes. Dried peaches are divided into two broad classes, namely "Muirs" and 
"Yellows," the latter including several yellow-fleshed, freestone varieties, principally 
the Lovell and Elberta. Dried peaches are sold both unpeeled and "Practically Peeled," 
the latter term designating peaches which have had the fuzzy skin removed after being 
dried. 

PEARS, California Sun Dried: 

Because of their distinctive shape, dried pears are graded by hand according to their 
size, color and general appearance into Extra Fancy, Fancy, Extra Choice, Choice 
and Standard grades for which no simple definitions can be given. 

PRUNES, California Sun Dried: 

Size Grades. No. per Pound. Diameter of Grader Holes. 

20 to 30 over 40/32 inches 

30 to 40 40/32 inches. 

40 to 50 38/32 inches. 

50 to 60 36/32 inches. 

60 to 70 33/32 inches. 

70 to 80 32/32 inches. 

80 to 90 30/32 inches. 

90 to 100 28/32 inches. 

100 to 110 26/32 inches. 

110 to 120 24/32 inches. 
120 and up below 24/32 inches. 

Quality Grades. Dried prunes are sold according to locality where grown, such as 
Santa Clara, Sacramento, San Joaquin, Sonoma or Napa Valleys. Two general quality 
grades are known: 

First. Uniform amber colored meat of fine flavor; skin in good condition and of 
deep black color. 

Second. Brown colored flesh, not so meaty and fine flavored; reddish brown colored 
skin. 

RAISINS, California Sun Dried: 
A. Muscat Raisins (with seeds). 



FRUIT AND VEGETABLE PRODUCTS 67 

1. Layers (unbroken bunches of perfect raisins), 
(a) Vineyard Run. 

(6) Layers (Three crown size), see below. 

(c) Clusters (Four crown size), see below. 

(d) Imperials (Six crown size), see below. 

2. Loose Muscats (stemmed raisins) : 

(a) One crown, 13/32 inches diameter. 

(6) Two crown, 17/32 inches diameter. 

(c) Three crown, 21/32 inches diameter. 

(d) Four crown, over 21/32 inches diameter. 

3. Seeded Muscats (above sizes of stemmed and seeded raisins): 

B. Sultanina Raisins (seedless): 

1. Natural (stemmed raisins): 

(a) First, plump raisins of even color and size. 

(b) Second, uneven color or size and not well filled out. 

2. Bleached (bleached to a light yellow color) : 

(a) Extra Fancy, fine large raisins of even yellow color. 

(b) Fancy, not perfectly bleached. 

(c) Choice, inferior to above grades. 

3. Oil and Soda Dipped. 

C. Miscellaneous Varieties. Sultanas, practically seedless; Valencias, bleached 
Muscats; Malagas and Feherzagos are stemmed and packed in the same way as loose 
Muscat raisins. 

D. Currants. Very small, stemmed, seedless raisins obtained from the Zante or 
Black Corinth grapes. 



ASSIGNMENT XXIV. EXPERIMENTAL DRYING OF 
FRUITS AND VEGETABLES 

Materials. Fresh fruits and vegetables in season as directed under 
''Procedure." 

Procedure : 

1. Comparison of Sun-drying and Dehydration. Prepare two trays 
each of apples and white potatoes as directed in Assignment XXV. 
Record the exact weight of material on each tray before and after prepa- 
ration. Place one tray of each product in a sunny location out of doors 
and record the loss in weight daily until sufficiently dry. Do not expose 
during moist weather. Place the other tray of each product in a small 
air-blast dehydrater at 150F., and record the loss in weight hourly 
until sufficiently dry. Plot the comparative rates of drying. Compare 
the cleanliness, color, flavor and odor of the refreshed and cooked prod- 
ucts. If procurable, interesting comparisons can be obtained by using 
a green vegetable, such as spinach or string beans, or fruits such as 
bananas, pears and berries. 

2. Effect of Lye-dipping. Weigh accurately two equal tray-loads of 
prunes, grapes or cherries. Dip one lot in boiling 0.5 per cent, sodium 
hydroxide solution until the bloom is removed and the skins slightly 
checked. Muscat and wine grapes require a 2.5 per cent, solution. Rinse 
in cold water and spread on a tray. Dry both trays in an air-blast 
dehydrater at 150 to 160F. Record the loss in weight hourly and 
plot the comparative rates of drying. Compare the dried samples as to 
color and flavor. 

3. Effect of Blanching. Prepare two weighed trays each of one or 
more products such as spinach, peas, cubed potatoes, sliced pumpkin, 
and cubed carrots. Blanch one tray of each in a steam box; potatoes 
3 minutes, other vegetables 5 minutes. Dry all trays in an air-blast 
dehydrater at 150F., plotting the hourly losses in weight. Compare the 
color and flavor of each before and after cooking. 

4. Effect of Sulphuring. Prepare two trays each of one or more 
products such as peeled and sliced apples, halved and pitted apricots or 
peaches, or peeled halved pears. Expose one tray of freshly prepared 
fruit to the fumes of burning sulphur for 1 hour. (Caution: Sulphured 
fruits must not be dried on metal trays. Use wooden slat-bottom trays.) 

68 



69 



Dry all trays in an air-blast dehydrater at 150F. and compare the 
color and flavor of the dried products. 

5. Effect of Size of Pieces on Drying. Prepare four trays of peeled 
and cored apples as follows: 

A. Halves, B. quarters, C. slices 14 inch thick, D. i/j-inch cubes. 




FIG. 11. Air Blast Dehydrater in Fruit Products Laboratory, University of Cali- 
fornia. A. Multivane fan; B, Air heating chamber; C, Drying chamber; D, Tray 
doors, E, Motor; F, Itecording thermometer. 

Place equal weights on each of the four trays and sulphur 30 minutes. 
Dry in an air-blast dehydrater at 150F., till each lot reaches the same 
degree of dryness (about 20 per cent, moisture). Plot comparatively the 
rates of drying from hourly weights and compare the dried samples as 
to color and flavor. 

6. Effect of Temperature of Air on Drying. Prepare three weighed 
trays of apples by peeling and coring, slicing or cubing and sulphuring 
30 minutes. Dry one tray at 120F., one at 150F., and one at 200F., 



70 LABORATORY MANUAL OF 

until sufficiently dry (about 20 per cent, moisture), keeping the humidity 
and velocity of air as constant as possible. Record results as in 5. 

7. Effect of Humidity of Air on Drying. Prepare two weighed trays 
of cubed and blanched potatoes or cubed and sulphured pears. Dry one 
tray in an air-blast dehydrater at 150F., with air of low relative hu- 
midity (below 10 per cent.). Dry the other tray with the same tem- 
perature and velocity of air, but increase the relative humidity of the air 
to at least 40 per cent. This may be accomplished by injecting the 
proper amount of steam into the heated air, measuring the humidity by 
a Hygrodeik or by wet and dry bulb thermometers. Record results 
as in Assignment XXIV 6. 

8. Effect of Velocity of Air on Drying. Prepare two weighed trays 
of cubed and blanched potatoes or cubed and sulphured apples. Dry 
one tray in an air-blast dehydrater at 150F., in a vigorous blast of air 
(500 to 1,000 linear feet per minute over trays, as measured with an 
anemometer) . Dry the other tray at the same temperature and humidity 
but in a mild flow of air (below 100 linear feet per minute) either in a 
natural draft evaporator or in an air-blast dehydrater with restricted 
air-flow. Record results as in Assignment XXIV 6. 

9. Comparison of Counter Current and Parallel Current Systems of 
Dehydration. Prepare two trays containing equal weights of apples, 
peeled, cored, cubed or sliced and sulphured. Dry one tray in an air-blast 
dehydrater, using an initial temperature of 210F., reducing the tem- 
perature as directed below to a finishing temperature of 160F. Dry the 
other tray at an initial temperature of 110F., and a finishing tempera- 
ture of 160F. In each case estimate the total weight of moisture which 
must be evaporated from the apples before being considered dry. At 
intervals of 30 minutes weigh each tray and increase or decrease the 
temperature by the number of degrees obtained by multiplying the total 
temperature range of 50 by the percentage of water lost, referred to 
the weight which must be evaporated. 

Example. Five hundred grams of prepared apples, with an estimated 
drying ratio of 5:1, must lose 400 grams of moisture in drying. After 
30 minutes at 210F., a loss of 100 grams in weight is noted, or 25 per 
cent, of the total moisture to be lost. Twenty-five per cent, of 50 is 
12.5. Consequently the temperature should be reduced to 197.5F. 
Similarly, if started at 110F., a loss in weight of 10 per cent, would 
indicate that the temperature should be raised to 115F. 

10. Effect of Moisture Content on Spoiling. Prepare three weighed 
trays each of one or more products such as (1) peeled, cubed and 
blanched potatoes, (2) peeled and sliced or cubed apples held in 2 per 
cent, brine for 5 minutes, (3) lye-dipped grapes or prunes, (4) peeled 
and sliced onions dipped in 2 per cent, brine or other materials prepared 



FRUIT AND VEGETABLE PRODUCTS 71 

as directed in Assignment XXV. Determine the approximate percentage 
of moisture in advance in a representative sample of the material to be 
dried as described in Assignment XXIII for apples. Calculate the weight 
of moisture which must be lost from each tray of material in order to 
obtain finished products of 15, 25, and 30 per cent, moisture, respectively, 
for fruits and 5, 15, and 25 per cent., respectively, for vegetables. Dry 
the trays at 150F. until the predetermined weight of material has been 
reached in each case; note the condition or "feel" of the product and seal 
in tin cans or glass jars stored in a dark place. After 6 weeks or more 
examine for evidence of spoilage or deterioration in quality. 



ASSIGNMENT XXV. PRACTICE IN FRUIT AND 
VEGETABLE DRYING 

Materials. Fresh fruits and vegetables in season as suggested in 
Table XL 

Procedure : 

1. Dehydration. Prepare and dry in an air-blast dehydrater or 
natural-draft "Home" evaporator several lots of fruits and vegetables in 
season as directed in Table XI. For each lot note the weight of raw 
material, loss in preparation and loss in drying. Vegetables should be 
dried until crisp or brittle (generally below 8 per cent, moisture). All 
fruits should be dried to a pliable leathery texture (approximately 20 
per cent, moisture), not hard and brittle, except berries and plums, which 
require quite thorough drying to prevent spoiling. Pack at once in 
insect-proof cans or cartons and store in a dry place. 

2. Sun-drying of Fruits. If fruits are available and climatic condi- 
tions favorable, such fruits as apricots, cherries, figs, grapes, peaches, 
pears and prunes may be sun-dried. The fruit should be prepared as 
in Table XI, except that fruit requiring sulphuring should be exposed 
to the fumes of burning sulphur for 3 to 4 hours. Grapes are usually 
sun-dried without dipping or sulphuring. Pears are usually sun-dried 
after merely cutting in half, sulphuring 24 to 72 hours and drying largely 
in the shade. After the fruit is two-thirds to three-fourths dry the trays 
should be stacked and the drying completed in the shade. When thor- 
oughly dry, empty the dried fruit into boxes and allow the moisture 
content to equalize for several weeks. Dip in boiling water 2 minutes, 
drain off the surface moisture and pack in insect-proof cans or cartons. 
Sulphured fruits are usually resulphured for several hours after dipping 
and before packing in order to preserve the color. 

3. Examination of Samples. After at least one month's storage, note 
the color and flavor of each of the dried products. Make a careful 
comparison of samples of the same variety of fruit, one sun-dried and 
the other dehydrated. Examination should be made both before and 
after preparation for the table as in Assignment XXIII-4. 

Suggestions : 

1. Dried fruits may be graded in accordance with the sizes given in 
Table X. 

72 



FRUIT AND VEGETABLE PRODUCTS 



73 



2. Dried products which have become insect-infested can be fumi- 
gated to destroy insect life by placing in a tight container together with 




Fia. 12. Natural draft home size evaporator. A, Heat spreader; B, Tray; C, Coa 

oil stove; D, Air outlet. 



a pan of liquid carbon bisulphide in the proportion of 1 pound per 100 
cubic feet until the carbon bisulphide has evaporated. 



74 



LABORATORY MANUAL 



TABLE XI. DIRECTIONS FOR DEHYDRATION OF FRUITS AND VEGETABLES 



Product 


Preparation for Tray 


Lbs. per 

Sq. Ft. 

on Tray 


Treatment on 
Tray 


Safe 
Finishing 
Temperature 


Apples .... 


Peel and core, then slice 


2 


Sulphur 30 min. 


165F 


Apricots 


or cube 
Halve and pit 


2 


Sulphur 60 min. 


160F. 


Bananas 


Peel, then halve length- 


1 to2 


Sulphur 30 min. 


165F. 


Berries, Black-, 
Logan - and 
Raspberries 
Berries, Straw-. . 
Cherries 


wise or slice crosswise 
Sort; wash if necessary 

Hull and sort 
Dip in boiling J^ per cent 


1 to 2 

1 to 2 
2 to 3 


Sulphur 15 min. 
(Optional) 

Sulphur 30 min. 
Sulphur white 


160F. 

160F. 
170F. 


Dates. . . . 


soda sol. 
Wash gently 


2 


cherries 20 min. 


140F. 


Figs.. 


Wash thoroughly 


2 to 3 


Sulphur Adriatic 


150F. 


Grapes, Sultana, 
Sultanina . . 


Dip in boiling % per cent 
lye sol., then rinse 


3 


figs 1 hr.; do 
not sulphur 
other varieties 
Sulphur 60 min. 


160F. 


Grapes, Muscat 
and Wine Va- 
rieties 
Peaches 


Dip in boiling 2}/ per 
cent lye sol., then rinse 

Halve and pit (peeling op- 


3 
3 


Sulphur 60 min. 
Sulphur 60 min. 


160F . 
150F. 


Pears 


tional) 
Peel; halve; core (cubing 


2 to3 


Sulphur 30 min. 


145F. 


Plums 


optional) 
Halve and pit 


2 to 3 


Sulphur 60 min. 


160F. 


Prunes ... . 


Dip in boiling J^ per cent 


3 to 4 




165F. 




lye sol. 








Beans; string. . . . 
Beets 


Prepare as for canning 
Prepare as for canning; 


2 
2 


Steam blanching 


160F. 
160F. 


Cabbage . . 


slice J4 inch thick 
Shred; blanch 2 min. in 


1 to2 




150F. 


Carrots 


boiling 1 per cent so- 
dium bicarbonate sol.; 
rinse 
Peel and cube 


2 


Blanch in steam 


150F. 


Sweet Corn 


Husk; blanch on cob in 


1 to2 


5 minutes 


160F. 


Onion 


boiling water 10 min.; 
cut from cob 
Peel; slice ^/g inch thick; 


1 




140F. * 


Peas 


dip in cold 3 per cent 
brine 
Prepare as for canning 


1 to2 


Steam blanching 


150F. 


Potatoes, Sweet. . 
Potatoes, White . . 
Pumpkin 


Peel; slice J4 inch thick 

Peel; slice or cube; dip in 
boiling water 2 min. 
Remove seeds; slice or 


1 to2 

1 to 2 
2 


(optional) 
Blanch in steam 
5 min. 
Steam blanching 
(optional) 
Steam blanching 


150F. 
150F. 
170F. 


Spinach . . . . 


shred into thin pieces 
Wash thoroughly 


1 


4 to 5 min. 


160F. 


Tomatoes . . 


Slice ^2 inch thick, or peel 


1 to2 


Sulphur 30 min. 


150F. 




and halve 




(optional) 





ASSIGNMENT XXVI. PRACTICE IN THE PREPARATION 
AND REFINING OF FIXED OILS 

Materials. Dry tomato seeds from Assignments IX and X, dry 
apricot pits 10 pounds, or dry cherry pits 5 pounds, and ripe olives 
(unpickled preferred) 20 pounds. Rancid oil, 1 quart. 

Procedure : 

1. Preparation. A. Pits. Weigh accurately about 4,000 grams of 
apricot pits or 2,000 grams of cherry pits. Crush the pits; separate the 
kernels and weigh. Grind the kernels fine with a food chopper and weigh. 

B. Tomato Seeds. Weigh the dry tomato seeds from Assignments 
IX and X carefully. If the seeds are not "bone dry," dry to constant 
weight at 140 to 150F. Grind thoroughly with a food chopper, using 
the grinding attachment. Weigh the ground material. 

C. Olives. Unpickled ripe olives are best, but pickled ripe olives will 
answer the purpose very well. Crush the weighed fruit thoroughly in a 
coffee-mill or heavy sample-grinder, crushing the pits and seeds as well 
as the flesh. Weigh the crushed fruit. 

2. Extraction of Oil by Pressure. A. Fruit Kernels. Heat the finely 
ground kernels to 100C. (212F.) in a steam box in layers about 2 
inches deep between the folds of a very heavy press-cloth. While still 
hot place the layers or "cheeses" of material between the wooden racks 
of a powerful press and subject to as high pressure as is attainable with 
the available equipment. A pressure of at least 500 pounds per square 
inch is desirable. Continue the pressing until no more oil is obtained. 
Grind the press cake; add a small amount (about 15 per cent.) of hot 
water; mix well; heat to 212F. and press a second time. Keep the oil 
from the two pressings separate. Allow the water and oil from the 
pressings to settle overnight. Separate the oil from the water by skim- 
ming or siphoning. Measure the oil obtained and reserve the press cake 
for Assignment XXVII. 

B. Olives. Press as directed in Assignment XXVI 2 A, but do not 
heat the fruit at any stage of the process. Do not mix the liquids from 
the two pressings. Allow the juice and oil to settle overnight and sepa- 
rate the oil from the juice by skimming or siphoning. Measure the yield 
of oil. 

3. Extraction by Solvent. Place the dry ground tomato-seeds in a 
Soxhlet or other continuous extractor and extract for 12 hours with pure 

75 



76 LABORATORY MANUAL 

benzene (benzol). Remove the solvent from the oil by distillation. 
Weigh the residual oil and note its character. 

4. Refining and Filtering Oils from Assignment XXVI 2 and 3. 
A. Kernel Oils. the oils from the first and second pressings. Note 

the flavor, color and odor of each. Determine the percentage of free oleic 
acid in a 10-gram sample by titration with N/10 sodium hydroxide as 
directed in Appendix, page 98. Weigh the oil and add exactly enough dry 
sodium carbonate (Na 2 C0 3 ) to neutralize the free acid. (One gram of 
sodium carbonate will neutralize 5.32 grams of free oleic acid.) Add also 
2 c.c. of water per 1,000 grams of oil and 2 per cent, by weight of finely 
ground bone-black or vegetable decolorizing carbon. Heat the mixture to 
390 to 200 F., and pass a stream of carbon dioxide through it at this 
temperature for 2 hours. Allow to stand overnight at room temperature. 
Filter through dry filter paper and determine the yield. Note the color, 
flavor and odor of each. Store each oil in a tightly stoppered bottle 
in a dark place for 3 months and again examine for flavor, color and odor. 

B. Olive Oil from Unpickled Olives. Oil from unpickled olives will 
be bitter. Mix the oil from each pressing separately with three times 
its volume of water at 100 to 105F. Allow to settle. Separate the oil 
from the water by skimming and repeat the washing and settling process 
until each oil is free from bitterness. Filter through dry filter paper. 
Store in tightly stoppered bottles in a dark place for 3 months and then 
note the flavor, color and odor of each. 

C. Olive Oil from Pickled Olives. Oil from pickled ripe olives is 
not bitter and requires no washing with water. Filter through dry filter 
paper; store and examine as in Assignment XXVI 4-JB. 

5. Refining Rancid Oil. Rancid oil can often be rendered edible by 
refining as directed in Assignment XXVI 4-A. If this treatment fails 
to remove all objectionable odor and flavor, maintain the oil at a tem- 
perature of 240 to 250F. and pass a stream of live steam through it 
for an hour ; cool and filter. 

Heating to 190F. with 3 to 4 per cent, of finely ground Fuller's Earth 
and filtering will sometimes remove objectionable odors and flavors. 



ASSIGNMENT XXVIL PRACTICE IN THE PREPARATION 
OF ESSENTIAL OILS 

Materials. Oranges or lemons, 100 pounds. Apricot kernel or cherry 
kernel press-cake from Assignment XXVI. Apricot or cherry pits 3 
pounds, or kernels 2 pounds. 

Procedure: 

1. Essential Oil from Oranges or Lemons. A. By Pressure. Weigh 
carefully about ^2 box of oranges or lemons. Remove the yellow portion 
of the rinds, including the oil cells, by grating down to the white "rag." 
Grind the gratings finely and place in a heavy cloth. Press under as 
heavy pressure as can be obtained and collect the juice. To the pomace 
add an equal volume of warm water; mix and press a second time. Do 
not mix the two pressings. Place the juice and oil of each in a large cen- 
trifuge tube and centrifuge until the oil and juice separate into distinct 
layers. Separate the oil from the juice by means of a glass separatory 
funnel. Filter the oil through dry paper to break the emulsion and to 
clear the oil. Measure the yield. Mix the two lots of oil and store in 
a, tightly stoppered bottle. If a centrifuge is not available allow the 
emulsions of juice and oil to settle overnight in tall tightly stoppered 
separatory funnels. 

B. By Solvent. Remove the oil cells from a weighed quantity of 
oranges or lemons by grating as directed in Assignment XXVII 1-A. 
Place the gratings in a wide-mouth glass-stoppered bottle. Add from 
a graduated cylinder sufficient low-boiling petroleum ether or ethyl ether 
to cover the product. Stopper tightly and allow to stand 8 to 10 hours with 
occasional agitation. Separate the solvent from the peels by heavy 
pressure. Separate the juice from the solvent by means of a separatory 
funnel. Place the solvent in a distillation flask resting in a water-bath 
and connect to a glass condenser. Distill at 50C. (122F.) until most 
of the solvent has been separated from the oil. Measure the volume of 
distillate and calculate the loss of solvent. Place the oil in a shallow 
beaker at room temperature until practically all odor of the solvent has 
disappeared. Determine the yield of oil and compare the quality with 
that from Assignments XXVII 1-4 and C 

C. By Distillation. Place gratings obtained as in Assignment XXVII 
1-A from a weighed quantity of lemons or oranges, in a large, heavy - 

77 



78 LABORATORY MANUAL OF 

walled bottle. Fit the bottle with a two-hole rubber stopper. Insert 
through the stopper a ^4-inch glass tube reaching to within ^4 inch of the 
bottom of the bottle. Connect this tube to a source of steam, such as a 
large flask of boiling water. Connect the bottle containing the peels to 
a glass condenser fitted to a large suction flask, the latter in turn con- 
nected to a vacuum pump. Insert the bottle with the peels in a large pot 
of water at 180 to 190F. and pass steam through the peels under a 
vacuum of 25 to 28 inches. Collect the distillate until no more oil collects 
in the receiving flask. Allow the distillate to stand overnight. Separate 
the oil by means of a separatory funnel and compare with oils from 
Assignments XXVII l-A and B. 

Store in glass bottles for 3 months and again compare the various 
samples. 

2. 'Bitter Almond" Oil from Apricot or Cherry Pits. A. Preparation 
of Press-Cake. Grind the press-cake from Assignment XXVI and weigh. 
To each 100 grams of the ground material add about 1,000 c.c. of water 
and boil gently for 20 minutes to extract the amygdalin. 

B. Addition of Kernels. Cool to 45C. (113 to 115F.) and add 
for each 100 grams of original dry press-cake 10 grams of finely ground 
apricot or cherry kernels, which have not been heated previously. The 
ground kernels are conveniently added after mixing in six or seven times 
their volume of cold water. Mix the kernels and boiled press-cake 
thoroughly and maintain at 45C. for 1 hour. 

C. Distillation. Transfer the mixture to a large bottle. Arrange for 
steam distillation as in Assignment XXVII 1-C, but do not use a vacuum 
pump. Distill at atmospheric pressure with the bottle containing the 
ground press-cake, etc., immersed in boiling water. Continue the distilla- 
tion until all of the bitter-almond oil has been removed, as indicated by 
the absence of milkiness in the condensed vapors. Place the distillate 
in a glass distillation flask and distill by boiling over a direct flame until 
one-half of the liquid has been distilled. Redistill this distillate (known 
as cohobation) three or four times, reducing the volume approximately 
one-half each time. Separate the oil from the remaining water by means 
of a separatory funnel and determine the yield. 

Caution. Prussic acid is formed during the process and distills with 
the bitter-almond oil (benzaldehyde). Do not inhale the vapors from 
the still. While the danger is not very great, unnecessary exposure to 
the prussic acid fumes should be avoided. 

Suggestions : 

1. The peeled lemons may be used for the preparation of citric acid 
in Assignment XXXI and the oranges may be used for juice or vinegar. 

2. Bitter-almond oil (benzaldehyde) is formed from the glucoside 



FRUIT AND VEGETABLE PRODUCTS 79 

amygdalin, the bitter principle of the kernels in fruit pits. The reaction 
is induced by the enzyme, EMULSIN, which also exists in the kernels. 
The reaction takes place very rapidly at 45 C., as follows: 

C 20 H 27 NOu +2H 2 O = HCN +C 6 H 6 CHO +2C 2 H 12 O 6 



Amygdalin + Water = Prussic Acid +Benzaldehyde -(-Glucose 



ASSIGNMENT XXVIIL EXAMINATION OF COMMERCIAL 

VINEGARS 

Materials. Samples of cider, grape, malt and distilled vinegars. 

Procedure : 

1. Appearance. Examine and compare the samples for color, clear- 
ness, sediment, flavor and odor. Hold a small sample in a test tube 
toward the light and examine carefully with a hand lens for presence 
of "vinegar eels" (minute nematode worms). 

2. Total Acid as Acetic. Transfer a 10-c.c. sample to a 100-c.c. 
volumetric flask. Dilute to mark with distilled water and mix. Deter- 
mine the acid in a 10-c.c. aliquot of the diluted sample as directed on 
page 98. Also determine the total acid by means of a Leo Acid Tester, 
following the directions accompanying the apparatus. 

3. Volatile Acid as Acetic. Place 10 c.c. of the vinegar in a porcelain 
evaporating dish on a steam bath. Evaporate almost to dryness. Add 
20 c.c. of water and evaporate again almost to dryness. Repeat addi- 
tions of water and evaporations at least five times. Take up the residue 
in water and titrate with N/10 sodium hydroxide. Report as fixed acid 
in terms of acetic acid. Total acid minus fixed acid gives the volatile 
acid as acetic acid. 

4. Extract. With a pipette place 25 c.c. of the vinegar in a tared 
evaporating dish about 200 mm. wide. Evaporate to a syrupy con- 
sistency over a steam bath. Dry 1 hour at 100C. in a drying oven and 
weigh. Calculate grams of extract per 100 c.c. 

5. Alcohol. Place 200 c.c. of the sample in a 500-c.c. distillation 
flask. Neutralize with concentrated sodium hydroxide, using litmus 
paper as an indicator. 

Distill about 95 c.c. into a 100-c.c. volumetric flask. Dilute to mark. 
Determine the specific gravity by means of a hydrometer, Westphal 
balance or pycnometer at 15%C. 

From the alcohol table in "Food Analysis" by Leach determine the 
corresponding alcohol content of the distillate. This figure divided by 
two gives the alcohol content of the vinegar. 

Alcohol in excess of % per cent, indicates incomplete acetic acid 
fermentation. 

6. Sugar. Determine total sugar after inversion as directed in the 
Appendix, page 100. 

80 



FRUIT AND VEGETABLE PRODUCTS 81 

Suggestions : 

1. Vinegar Standards. A. Pure cider vinegar contains in each 100 
c.c. not less than 4 grams of acetic acid, 1.6 grams of extract (of which 
not more than 50 per cent, is reducing sugars) , and .25 grams apple ash. 

Diluted cider vinegar must contain not less than 4 grams of acetic 
acid per 100 c.c., but need not conform to the other standards if labeled 
"diluted." 

B. Malt vinegar contains in each 100 c.c. not less than 4 grams of 
acetic acid, 2 grams of solids and 0.2 grams of ash. 

C. Wine vinegar or grape vinegar contains in 100 c.c. not less than 
4 grams of acetic acid, 1.0 gram of grape solids and 0.13 grams of 
grape ash. 

D. Distilled vinegar, spirit vinegar or grain vinegar is made by the 
acetification of dilute alcohol and contains in 100 c.c. not less than 4 
grams of acetic acid. 

An exact interpretation of the above standards would require that 
the 4 grams of acid per 100 c.c. be all acetic acid. In practice, however, 
the total acid is determined and calculated as acetic, although part of 
the total acid may be due to other organic acids. The addition of min- 
eral acids to vinegar is prohibited. 

2. Definition of "Grain Strength." The trade usually designates the 
strength of vinegar by "grains" instead of in percentage. A "40-grain 
vinegar" contains 4 grams of total acid per 100 c.c. calculated as acetic 
acid. That is, "10 grains" is equivalent to "1 gram of acid as acetic per 
100 c.c." 



ASSIGNMENT XXIX EXPERIMENTAL PREPARATION 
OF CIDER VINEGAR 

Materials. Twenty pounds of apple culls. 

Procedure : 

1. Preparation of Pure Yeast Starter. Obtain a pure culture of cider 
yeast (Saccharomyces ellipsoideus or S. malei) on agar. Add a small 
amount of sterile cider. Incubate 3 to 4 days at 80 to 90F. Transfer 
the actively fermenting culture to 500 c.c. of sterile cider in a cotton- 
plugged flask and incubate at 80 to 90F. until in active fermentation. 

2. Crushing and Pressing. Extract the juice from a weighed amount 
of apple culls as directed in Assignment XIII. Determine the yield, 
acidity of the juice, and Balling degree. 

3. Alcoholic Fermentation. Divide into two equal portions and place 
each half in a 1-gallon stoneware crock. Place both crocks in an incu- 
bator at 80 to 90 F., or in a warm room. 

A. Spontaneous Fermentation. Cover one crock with cheese cloth 
and allow to undergo fermentation without addition of yeast. 

B. Pure Yeast Fermentation. To the second crock of juice add the 
actively fermenting pure yeast culture from Assignment XXIX 1 at the 
rate of 50 c.c. per 1,000 c.c. of cider. Mix thoroughly. 

Determine the Balling degree of each lot daily until fermentation 
ceases. Fermentation will usually be complete in 2 to 3 weeks. Examine 
samples of each juice under the high power of the microscope on the 
second and third days of fermentation and make sketches of micro- 
organisms found. 

Determine the alcohol and sugar in the fermented juices as directed 
in Assignment XXVIII. Calculate the yield of alcohol per gram of 
sugar fermented in each case. 

4. Acetic Fermentation. Decant the fermented liquids from the 
yeast sediment and strain through several thicknesses of cheese cloth. 
Rinse the containers used for alcoholic fermentation and return the fer- 
mented liquids to them. 

Allow lot 3- A (spontaneously fermented juice) to remain untreated. 

To lot 3-5 add one-fourth its volume of bulk cider vinegar (not pas- 
teurized bottled vinegar). 

Determine the acidity of each lot. Cover both crocks with cloth 
to exclude vinegar flies and place in an incubator at 80 to 90F. or in 

82 



FRUIT AND VEGETABLE PRODUCTS 83 

a warm room. Determine the acidity of each at intervals of one week 
until there is no longer any increase in acidity. 

Determine the residual alcohol as directed in Assignment XXVIII. 
Calculate the amount of alcohol oxidized during acetic fermentation. 

5. Clarification. A. Filtration. Determine the rate of filtration of 
100 c.c. portions of each vinegar through a small filter paper. To 100 
c.c. portions add 2 grams of "Filter eel" or other infusorial earth, and 
to a third 100-c.c. portion of each add 4 grams of this material. Mix 
well and again determine the rate of filtration of each. Compare the 
clearness and flavor of the filtrate from each lot. 

B. Clarification with Isinglass. Prepare a 2 per cent, solution of 
Russian isinglass (fish glue) or other good grade of isinglass by soaking 
2 grams of the material in 100 c.c. of vinegar for 24 hours and grinding 
in a mortar until dissolved. 

To 100-c.c. lots of each vinegar add the following amounts of isinglass 
by means of this solution: 

(1) 5 grams per hectoliter 0.25 c.c. per 100 c.c. 

(2) 10 grams per hectoliter 0.50 c.c. per 100 c.c. 

(3) 20 grams per hectoliter 1.00 c.c. per 100 c.c. 

(4) 40 grams per hectoliter 2.00 c.c. per 100 c.c. 

(5) 80 grams per hectoliter 4.00 c.c. per 100 c.c. 

Shake thoroughly and allow to stand 48 hours. Compare results. 
To lots which have not settled add 1,000 grams Spanish Clay per hecto- 
liter as directed in 5-C and note results. 

C. Spanish Clay. Prepare a 10 per cent, suspension of Spanish Clay 
as directed in Assignment XII-6-C. To 100-c.c. lots of each vinegar 
add the following amounts of this clarifying agent (dry basis) : 

(1) 100 grams per hectoliter 1 c.c. per 100 c.c. 

(2) 200 grams per hectoliter 2 c.c. per 100 c.c. 

(3) 400 grams per hectoliter 4 c.c. per 100 c.c. 

(4) 800 grams per hectoliter 8 c.c. per 100 c.c. 

(5) 1GOO grams per hectoliter 16 c.c. per 100 c.c. 

Allow to stand 48 hours and compare results. 

6. Pasteurizing. Combine the clear vinegar from 4-^4, 4-B, and 4-C, 
keeping the two original lots of vinegar separate. Bottle and seal with 
crown caps. Pasteurize one-half of each lot at 140F. for 20 minutes. 
Place all bottles in an incubator at 80 to 90F., or in warm rooms 
for several months. Compare the clearness of pasteurized and unpas- 
teurized samples. 

Suggestions. Data from alcoholic and acetic fermentations should 
be plotted on coordinate paper in order to indicate the relative rates and 
completeness of fermentation. 



ASSIGNMENT XXX. PRACTICE IN THE PREPARATION 
OF FRUIT VINEGARS 

Materials. Cull fruit, such as apples, oranges, grapes, pears, peaches 
or prunes, 50 pounds. 

Procedure: 

1. Preparation of Yeast Starter. Prepare about 1,000 c.c. of pure 
cider yeast starter as directed in Assignment XXX- 1. 

2. Preparation of Fruit. A. Juicy Fruits. Crush and press juicy 
fruits, such as oranges, grapes and apples, as directed in Assignment 
XIII. Record the weight of the fresh fruit and pomace and the volume 
of juice. Determine the acidity and Balling degree of each juice and 
place each in a stoneware crock. Dry the pomace in an air-blast dehy- 
drater and determine the yield of dried material. 

B. Pulpy Fruits. Thoroughly crush a pulpy fruit, such as peaches, 
pears or prunes, into a stoneware crock. Press out a small quantity of 
the juice and determine the acidity and Balling degree. If the Balling 
degree exceeds 20 add a calculated amount of water to reduce it to 20. 
Record the weight of fresh fruit used. Do not press until after pre- 
liminary fermentation has taken place. 

3. Fermentation. A. Juice. To each 1,000 c.c. of fresh juice add 
50 c.c. of an actively fermenting pure yeast culture. Mix thoroughly and 
cover the crock with a cloth to exclude vinegar flies. Store in a warm 
place at 80 to 90F. and allow to stand until fermentation ceases. Take 
the Balling degree of each fermenting juice daily and plot the rate of 
fermentation. Fermentation should be complete within 15 days. 

B. Pulpy Fruits. To the crushed pears or other pulpy fruit add 50 
c.c. of actively fermenting pure yeast starter per 1,000 grams of fruit. 
Mix thoroughly and cover the crock with cloth. Stir vigorously twice 
daily until the fruit is thoroughly softened by fermentation (usually 4 
to 5 days). Determine the Balling degree daily. Press out the juice, 
weigh the pomace and measure the volume of juice obtained. Allow the 
fermentation to proceed as in 2-A until there is no further reduction in 
Balling degree. Record the Balling degree and plot the rate of fermen- 
tation. 

4. Clearing the Fermented Juice. Separate the fermented juice from 
the yeast sediment and filter it through a juice filter or filter paper. 

5. Dilution and Addition of Acid. Determine the total acid and 

84 



FRUIT AND VEGETABLE PRODUCTS 85 

alcohol content of the fermented juice as directed in Assignment XXVIII. 
If the alcohol is in excess of 6 per cent, reduce it to this percentage by 
the addition of a calculated amount of water. 

To each 1,000 c.c. of the liquid add 250 c.c. of strong unpasteurized 
fruit vinegar. 

6. Acetification. Store the filtered and acidified liquid at 80 to 
85 F. in a stoneware crock covered with cheese cloth. Determine the 
total acidity weekly until there is no longer any increase. Plot the rate 
of acetic fermentation. 

7. Clearing and Bottling the Vinegar. Filter the vinegar and meas- 
ure its volume. Calculate the yield of vinegar in gallons per ton of fresh 
fruit. 

Bottle the vinegar in crown-finish bottles and seal with crown caps. 
Pasteurize as directed in Assignment XXIX-6. 

Suggestions: 

1. Dried unsulphured fruits may be used for the preparation of vin- 
egar if soaked until soft in sufficient water to reduce the sugar percentage 
to 20 and then crushed and fermented as directed for pulpy fruits. 

2. Potatoes (sweet or white) may be used in the same manner as 
pulpy fruits for vinegar making if first thoroughly cooked in a steam 
retort at 5 pounds pressure, to gelatinize the starch, and then heated 
at 60C. (140F.) with 5 per cent, of ground barley malt until the starch 
is converted to sugar. Complete conversion of the starch to sugar is 
shown by the absence of blue color when a drop of the "mash" is mixed 
with a drop of dilute iodine solution. 



ASSIGNMENT XXXI. PRACTICE IN THE PREPARATION 
OF SAUERKRAUT AND PICKLES 

Materials. Cabbage 25 pounds and cucumbers 30 pounds. 

Procedure . 

1. Sauerkraut. Select only mature sound heads of cabbage. 

A. Preparation. Cut in quarters and remove the core. Shred by 
hand with a large knife or by means of a vegetable slicer. 

B. Salting. Mix the shredded cabbage thoroughly with fine salt at 
the rate of 2 ounces (about 60 grams) of salt for each 5 pounds of cab- 
bage. Pack firmly, but not too tightly, in a 3-gallon stoneware crock. 
Cover with a clean table-plate or circular piece of board slightly smaller 
in diameter than the crock. Place a heavy weight on the cover so that 
after 24 hours the level of the brine formed by the salt and cabbage 
juice is above the cover. Do not use lime stone. 

C. Fermentation. Place the crock in a warm room or in an incu- 
bator, preferably at about 86F. Remove scum occasionally. When 
fermentation is complete, usually 6 to 8 days, determine the acidity of 
the brine by titration of a 10-c.c. sample as directed in Appendix, 
page 98. 

D. Canning. Fill two glass-top fruit-jars completely with the fin- 
ished sauerkraut; add brine from the fermentation crock to fill the jars 
to overflowing. Seal and store without sterilization. 

Place the remainder of the kraut into cans, completely full. Add 
brine from the fermentation crock to fill the cans completely, or if there 
is insufficient fermented brine, add a 3 per cent, brine. Exhaust 5 
minutes in live steam, seal and sterilize 25 minutes in boiling water. 
Store and compare with unsterilized samples after one month. 

2. Salt Pickles. A. Preparation. Wash the fresh cucumbers and 
place about 12 pounds in a 4-gallon crock. Cover with a 10 per cent, 
brine (40 salometer). Cover as directed for sauerkraut and weight the 
cover sufficiently to keep the cucumbers submerged in the brine. 

B. Fermentation. Store at room temperature. At weekly intervals 
for a period of 6 weeks place y pound of salt on the cover for each 6 
quarts of brine. Salt placed on the cover dissolves gradually and is 
distributed evenly in the brine. The surface of the brine must be 
skimmed occasionally to prevent putrefaction and loss of acid. When 

86 



FRUIT AND VEGETABLE PRODUCTS 87 

the curing process is complete the cucumbers should be firm in texture 
and should have changed in appearance from opaque white to trans- 
lucent. The bright green color of the fresh cucumbers becomes an olive 
green. Six to eight weeks are usually required for proper curing. Cu- 
cumbers in this condition are known as "salt stock" and are used in the 
preparation of sour or sweet pickles as directed in Assignment XXXI 
3 and 4. Salt stock will keep indefinitely if the brine is skimmed fre- 
quently to prevent excessive growth of film yeast. 

3. Processing Salt Pickles. A. Removal of Salt. Place the salted 
cucumbers from Section 2 in a large pot. Cover with water at about 
120F. Place the pot on a hot plate and maintain at this temperature 
for 10 to 12 hours. Repeat this extraction until most of the salt is 
removed as indicated by the taste. 

B. Grading. Grade the cucumbers into two sizes. Use the large 
size for sour pickles and reserve the small size for sweet pickles. 

4. Sour Pickles. A. Addition of Vinegar. Cover the large pickles 
from Assignment XXXI 3 with distilled vinegar of 4 to 6 per cent, acetic 
acid. Allow to stand until the vinegar has penetrated the pickles 
thoroughly. 

B. Canning. Fill one glass jar with tne pickles and vinegar. Seal 
but do not sterilize. 

Put the remainder of the pickles into double-lacquered cans. The 
cans should be filled completely with vinegar. Exhaust in live steam 
J2 to 15 minutes. Seal hot. No further sterilization is required. 

5. Sweet Pickles. A. Preliminary Treatment. Cover the small 
pickles from Assignment XXXI 3 with distilled vinegar containing 4 to 
4y per cent, acetic acid and allow to stand about 10 days. Drain the 
vinegar and in it dissolve 3 pounds of sugar per gallon, in which immerse 
the pickles again for about one week. 

B. Addition of Spices. Remove the vinegar and add about 20 grams 
of mixed whole spices (obtainable from any grocery store) per gallon. 
The spices most commonly used are black pepper, cayenne pepper, cloves, 
cinnamon, celery seed, caraway seed, dill seed, mustard, allspice, carda- 
mom, bay leaves and coriander. Heat to the simmering point for about 
Vi> hour. Add fresh vinegar to replace that lost by evaporation, strain 
out the spices, and add sugar at the rate of 3 pounds per gallon. Cover 
the pickles with the spiced vinegar and allow to stand about one week. 
Can as directed in Assignment XXXI 4. 

6. Dill Pickles. Select and wash large fresh cucumbers uniform in 
size. 

A. Packing. Place a layer of dill herb and V-j ounce of mixed dill 
pickle spices in the bottom of a 4-gallon crock. Fill the crock within 
2 or 3 inches of top and add another layer of dill and Vi> ounce of spices 



88 LABORATORY MANUAL 

B. Brining. Cover with a brine consisting of 1 pound of salt and 
iy 2 pints of vinegar to 2M> gallons of water. Cover with a weighted 
plate or board. 

C. Fermentation. Store at a temperature of about 86F. and skim 
occasionally. Fermentation should be complete within 10 to 14 days. 

4. Canning. Can as directed in Assignment XXXI 4. 

Suggestions. Small (pearl) onions, cauliflower, green tomatoes, and 
string beans are prepared for pickling by 6 to 8 weeks' storage in brine 
strong enough (15 per cent, salt) to prevent fermentation. They may 
then be converted into sour or sweet pickles as directed in Assignment 
XXXI 4 and 5 and mixed in any desired proportion with cucumber pickles. 



ASSIGNMENT XXXIL PRACTICE IN THE PREPARATION 

OF FRUIT ACIDS 

Materials. Twenty-five pounds of lemon or lime culls. One-half 
pound of crude grape argol; i. e., crystalline sediment from grape juice 
or wine. 

Procedure : 

1. Citric Acid. A. Extraction of Juice. Crush and press the juice 
from 25 pounds of lemon culls. To the pomace add 4,000 c.c. of water. 
Mix well; press a second time. Mix the liquids from the two pressings. 
Weigh the pomace and measure the volume of the combined extracts. 

B. Fermentation. Place the juice in a stoneware crock and add a 
cake of compressed yeast. Mix the yeast thoroughly with the juice. 
Cover with a cloth and allow to ferment at room temperature one week. 

C. Filtration. Add 2 grams of finely pulverized "Filter Cel" per 
100 c.c. of fermented juice and bring to boiling. Allow to settle for 
24 hours. Decant off the clear liquid and filter if necessary. Filter the 
cloudy liquid and sediment through coarse filter paper and combine the 
clear liquids. Measure the volume. 

D. Neutralization. Determine the percentage of citric acid in the 
juice by titration as directed in Appendix, page 98. Calculate from the 
following reaction the amount of precipitated chalk (calcium carbonate) 
required to neutralize the acid, and add 5 per cent, in excess to the liquid. 

Citric Acid+Calcium Carbonate = Calcium Citrate + Water +Carbon Dioxide 
2CJI 8 O7 +3CaCO 3 =Ca s (C,H 8 O 7 )2 +3H 2 O +3CO 2 

384 Cms. +300 Cms. =474 Cms. +54 Cms. + 132 Cms. 

Mix well. Boil until evolution of carbon dioxide gas ceases. Filter 
through filter paper while still boiling hot. Wash the precipitate on the 
filter with a small amount of boiling water. 

E. Decomposition of Calcium Citrate. Transfer the precipitate to 
a large beaker and add sufficient water to make a thin paste. 

Add sulphuric acid (20 per cent, solution) slowly with constant stir- 
ring until a drop of the liquid placed on a piece of methyl violet indicator 
paper changes the color of the indicator to blue. To prepare the indi- 
cator paper dip small strips of filter paper in dilute methyl violet solution 
and allow to dry at room temperature. 

F. Filtration. Filter through filter paper to remove calcium sul- 
phate. Wash precipitate with a small amount of cold water. 

89 



90 LABORATORY MANUAL OF 

G. Concentration. Place the filtrate in a large, heavy-walled flask 
connected to a condenser and vacuum pump. Concentrate by boiling in 
vacua to a density of 20 to 25 Baume (test made at 50C.). Transfer 
to a large beaker and allow to cool to room temperature and settle. Filter 
off the precipitated calcium sulphate and return the filtrate to the 
vacuum flask. Concentrate in vacuo to 37 to 39 Baume (test made at 
50C.). 

H. Crystallization. Transfer the liquor to a heavy-walled beaker 
or small stoneware jar and allow to cool and crystallize for one week. 
Stir two or three times daily. 

1. Separation from Mother Liquor. Separate the crystals from the 
mother liquor by draining through cloth. This gives "brown crystals." 
The mother liquor still contains recoverable citric acid, but in this assign- 
ment may be neglected and the mother liquor discarded. 

J. Decolorization. Dissolve the drained crystals in a small amount 
of distilled water and dilute to 20 to 25 Baume. Add 3 per cent, by 
weight of finely ground vegetable decolorizing carbon such as "Noirit" 
or "Eponit." Stir and heat to boiling. Filter free of carbon. A water- 
white filtrate should be obtained. Wash the carbon on the filter with a 
small amount of hot water and combine the filtrates. 

K. Concentration of decolorized liquor. Concentrate in vacuo to 
36 to 37 Baume (test made at 50C.) and allow to crystallize as di- 
rected in Assignment XXXII 1-7. 

L. Drying. Separate the crystals from the mother liquor and allow 
to dry in the air several days. Weigh and calculate the yield of citric 
acid in pounds per ton of fresh fruit. The mother liquor contains re- 
coverable citric acid but in this assignment may be discarded. 

2. Cream oj Tartar. A. Dissolving Cream of Tartar. Weigh 200 
grams of finely ground crude "argol" and mix with about 5,000 c.c. of 
distilled water. Boil 10 minutes and filter through cloth until fairly 
clear. 

B. Concentration. Concentrate by boiling to about 1,000 c.c. 

C. Crystallizing. Set aside in a cool place and allow to crystallize 
for 4 to 5 days. Separate crystals from mother liquor by decantation. 

Concentrate the mother liquor in vacuo to about 200 c.c. and allow 
to crystallize as above. Combine the two lots of crystals and discard 
the mother liquor. 

D. Decolorizing. Dissolve the crystals in about 5,000 c.c. of water 
and add 1 per cent, by weight of vegetable decolorizing carbon. Boil 5 
minutes and filter through paper. 

E. Concentration and Crystallizing. Concentrate in vacuo to about 
1,000 c.c. Pour into a beaker and allow to crystallize several days. Re- 
move the mother liquor and dry the crystals in the air. Concentrate the 



FRUIT AND VEGETABLE PRODUCTS 91 

mother liquor to about 200 c.c., crystallize; separate the crystals and dry 
in the air. Weigh the air-dry crystals from both lots and calculate the 
total yield in percentage. 

Suggestions: 

1. Tartaric acid may be prepared from the crude argol or cream of 
tartar in a method analogous to that for citric acid. 

2. Tartaric acid may be prepared synthetically from carbon dioxide 
and water by a patented electrolytic process. 

3. Crude argol may be obtained from any grape-juice factory or 
cream-of -tartar refinery. 



ASSIGNMENT XXXIIL PRACTICE IN OLIVE PICKLING 

Materials. Thirty-five pounds of ripe olives of a commercial variety 
such as Mission, Manzanillo or Sevillano. Ten pounds of green olives, 
preferably Sevillano or Manzanillo. 

Procedure : 

1. Grading. Grade the olives by screens or by hand, as suggested in 
Table XII. Record the weight of each size. 

2. Storage. If the olives can not be pickled immediately after grad- 
ing place them in a brine of 10 per cent. salt. Store in a cool place. If 
the olives float, place a weight upon them to hold them beneath the 
surface; or seal in glass jars. Olives after storage in brine must be 
soaked in several changes of water for 24 hours before pickling. 

3. Pickling Ripe Olives by Usual Commercial Process. A. First Lye. 
Prepare a lye (sodium hydroxide) solution containing for Mission 
olives 2 per cent, sodium hydroxide and for Manzanillo and Sevillano 
varieties iy 2 per cent. Cover the olives in a crock with this solution at 
a temperature of 65 to 75F. Allow to remain until the lye has barely 
penetrated the skin of the fruit as evidenced by discoloration of the skin 
and flesh. It should not be allowed to penetrate more than 1/16 inch 
into the flesh. This will, at the temperature given above, usually require 
3 to 5 hours. Discard the lye. 

B. First Exposure. Allow the olives to remain exposed to the air 
until an even black color is obtained. Stir the olives at least three times 
daily. Three to five days' time will be required. 

C. Subsequent Lye Treatments and Exposures. Cover the olives 
with a 0.5 per cent, lye solution and allow to penetrate about one-fourth 
way to the pit. A drop of phenolphthalein indicator placed on the cut 
surface of the fruit will indicate the depth of penetration of the lye. 
Remove and discard the lye. Expose the olives to the air 24 hours. 
Cover again with a 0.5 per cent, lye solution and allow to penetrate about 
% to pit. Remove and discard the lye. Expose the olives again to the 
air for 24 hours. Cover the olives again with a 0.5 per cent, lye solution 
and allow it to penetrate completely to the pit. Remove and discard 
the lye. Expose the fruit again for 24 hours to the air. 

D. Washing. Cover the olives with water and change the water 
twice or three times daily until all lye is removed from the flesh of the 

92 



FRUIT AND VEGETABLE PRODUCTS 93 

fruit. (This is determined by applying a drop of phenolphthalein to the 
cut surface; or by taste). 

E. Brining. Place the olives in a 3 per cent, salt brine for two days. 

F. Filling and Exhausting. Fill cans with the olives, after careful 
sorting. Add hot 3 per cent, brine and exhaust in steam for 6 minutes. 

G. Sterilization. Seal and sterilize in a retort at 240 F. for 40 
minutes. 

4. Pickling Ripe Olives by the Aerated Water Process. Put ripe 
olives in a -3-gallon stoneware crock until about two-thirds full. Cover 
with a iy 2 per cent, lye (sodium hydroxide) solution. Insert a glass 
tube to the bottom of the container and connect the tube to a supply of 
compressed air. Pass air through the liquid vigorously until the lye has 
penetrated the skin of the olives and has entered the flesh of the olives 
to a depth of 1/32 inch. Remove the lye and replace it with water. 
Continue the aeration of the liquid, changing the water twice daily. At 
the end of two days cover the olives with a % per cent, lye solution 
and allow it to penetrate about one-half way to the pit, aerating the 
liquid continuously during this treatment. Replace the lye solution 
with water and continue the aeration for another 24 hours. Again add 
a ^ per cent, lye solution and allow it to penetrate nearly to the pits of 
the fruit. Replace it with water for 24 hours. Finally place a ^ per cent, 
lye solution on the olives and allow it to penetrate to the pit. Replace 
the lye with water, which should be changed twice daily until the olives 
are free from lye. Cover the olives with a 3 per cent, salt solution and 
allow them to stand 24 hours. During all lye, water and brine treat- 
ments continue the aerating process. Can and sterilize the pickled olives 
as directed in Assignment XXXIII 3. Compare the flavor and general 
quality with the olives from Assignment XXXIII 3. 

5. Pickling Ripe Olives by the Greek Process. Use large thoroughly 
ripe olives. Mix the olives with one-fourth their weight of coarsely 
crushed rock-salt in a wooden box equipped with a perforated bottom to 
permit escape of brine formed during pickling. Cover the olives with a 
layer of crushed rock-salt about */ inch thick, this salt being in addition 
to that mixed with the fruit as directed above. Allow the mixture of 
olives and salt to stand in a cool place until the fruit has developed the 
characteristic wrinkled appearance of commercial Greek olives and until 
most of the bitterness has disappeared. The time usually required is 
about G weeks. The salt and olives should be thoroughly mixed once a 
week during the curing period. Pack the finished product in jars or 
small wooden boxes with about 10 per cent, of its weight of coarsely 
crushed rock-salt. 

6. Green Olives by Fermentation Process. Use hard green olives 
which have attained full size. The Sevillano olive is best for the prepa- 



LABORATORY MANUAL 



ration of green olive pickles. Cover the olives in a stoneware crock with 
a 11/2 per cent, lye solution (sodium hydroxide). Allow the lye to pene- 
trate about three- fourths the distance to the pits of the fruit. Remove 
and discard the lye. Cover the olives immediately with water twice 
daily until the fruit is free from lye. Place the olives in a small wooden 
keg or wooden pickle bucket of convenient size or in a large fruit jar. 
Fill the container completely with a brine of 9 per cent, salt and con- 
taining 1/10 of 1 per cent, acetic acid from vinegar. Seal and set aside 
at room temperature until the olives have developed the flavor desired. 
Two to three months' time will usually be sufficient for the completion 
of the necessary lactic acid fermentation. 

Suggestions. The relation of the diameter of olives to the commer- 
cial size grades is shown by the following table: 

TABLE XII. RELATION OF SIZE GRADES AND DIAMETER OF RIPE OLIVES 



Grade 


Number 
Per Pound* 


Diameter in 
Inches 


Grade 


Number 
Per Pound* 


Diameter in 
Inches 


Small 


120-135 


9/16 


Mammoth . 


65-75 


13/16 


Medium 


105-120 


10/16 


Giant 


55-65 


14/16 


Large 


90-105 


11/16 


Jumbo 


45-55 


15/16 


Extra Large . . . 


75- 90 


12/16 


Colossal. . . . 


35-45 


16/16 



* The relatively wide range in "number per pound" is necessary to include all 
varieties of olives of different shapes. 



ASSIGNMENT XXXIV. PRACTICE IN THE PREPARA- 
TION OF MUSEUM SPECIMENS 

Materials. Freshly gathered specimens of fruits and vegetables as 
perfect in shape, color and condition as possible. Perfect specimens of 
large size and free from blemishes give the best results. 

Procedure: 

1. Green Colored Products (such as artichokes, string beans, peas, 
spinach, green leaves, cucumbers, green almonds, and hard green fruits). 
The preservation of the green color (chlorophyll) of plant tissues depends 
upon fixation of the color with copper salts. 

A. Fixation of Chlorophyll Color. Immerse in a 5 per cent, copper 
sulphate solution until the color has been fixed as indicated by a definite 
deepening of the tint. This will require 24 hours or less. 

B. Storage Solution. Remove the specimens from the copper sul- 
phate solution, rinse in running water for 2 to 3 hours to remove excess 
copper sulphate. Rinse in distilled water and store in a glass jar filled 
with a solution containing 1 ounce of 6 per cent, sulphurous acid per 
gallon of distilled water. The jar should be well sealed to prevent loss 
of the sulphurous acid and the solution renewed once every 6 months. 

2. Tomatoes and Red Peppers. Store specimens of uniform red color 
and firm texture in the following solution: 

Distilled water. ... 1 gallon Sulphurous acid 6 per cent, solution. .1/8 ounce 

Salt 2 ounces Potassium nitrate 1/4 ounces 

Formalin 1/4 ounce Glycerine 8 ounces 

Green leaves should be fixed separately in 5 per cent, copper sulphate 
solution before placing in the above solution. 

3. White Vegetables (corn on cob, cauliflower, asparagus, dry onions, 
celery, turnips, summer squash, etc.) can be preserved in the following 
solution: 

Distilled water 1 gallon Potassium nitrate. ... 1 ounce 

Sulphurous acid 6 per cent, solution ... 1 ounce Salt 3 ounce 

Copper sulphate to give a faint green solution. 

4. Citrus Fruits (oranges, grapefruit, lemons, and limes) retain their 
color and form satisfactorily in the following solution: 

Water 1 gallon Sulphurous acid 6 per cent, solution 1/2 ounce 

Formalin 1/8 ounce Boric acid 1 ounce 

Copper sulphate to give a faint green solution. 
95 



96 LABORATORY MANUAL 

5. White Grapes, Ripe Pears and Yellow Apples. Store in the fol- 
lowing solution. No preliminary fixation of color is necessary. 

Distilled water 1 gallon Boric acid 1 ounce 

Potassium nitrate 1/8 ounce Glycerine 6 ounces 

Copper sulphate to give a faint green solution. 

6. Black Grapes and Other Black Fruits (such as ripe prunes, Damson 
plums, black cherries, etc.). Store in the following solution. No pre- 
liminary fixation of color is necessary. 

Distilled water 1 gallon Boric acid 1 1/2 ounces 

Formalin 3 ounces Salt (Na Cl) 3 ounces 

Glycerine 6 ounces 

7. Berries, Peaches, Apricots, Red or White Cherries, Red Grapes and 
Other Red Fruits. Fix the color in the following solution until the red 
color has changed to a uniform purple, but do not prolong the treatment 
beyond this point; 24 to 36 hours is usually sufficient. 

Distilled water 1 gallon Formalin 1/2 ounce 

Sulphurous acid 6 per cent, solution 1 ounce Glycerin 10 ounces 

When the color has been fixed, store the specimens in the following 
solution : 

Distilled water 1 gallon Sulphurous acid 6 per cent, solution 1 ounce 

. Renew this solution once each 6 months. 

Suggestions: 

1. Except with specimens of green color, leaves should be fixed sepa- 
rately from the fruit specimens in 5 per cent, copper sulphate solution. 
The fruit after fixation in a suitable solution can be tied to the branches 
by means of thread. Delicately tinted fruits if placed in 5 per cent, 
copper sulphate solution usually develop an undesirable brown color, and 
green leaves if placed directly in the solutions used for fruits either 
become brown in color or bleached. 

2. In all cases where glycerine is recommended, it may be replaced 
by cane sugar to increase the Balling degree of the liquid to approxi- 
mately that of the juice of the fruit. For grapes this is about 20 to 22 
Balling and for most other fruits 12 to 15 Balling. 



METHODS OF ANALYSIS 

1. Preparation of Standard Acid and Alkali Solutions: 

A. Tenth-normal Hydrochloric Acid. Dilute 8.6 c.c. of concentrated 
hydrochloric acid C.P. to 1,000 c.c. with distilled water in a volumetric 
flask. 

Weigh exactly 2.6500 grams of anhydrous sodium carbonate C.P. in 
a small beaker and wash into a 500-c.c. volumetric flask with distilled 
water and dilute to exactly 500 c.c. Mix thoroughly. The distilled water 
should be freed from carbon dioxide by previous boiling and cooling. 

Pipette exactly 20 c.c. of this N/10 sodium carbonate solution into 
a beaker or flask, add a few drops of methyl orange indicator (0.2 grams 
in 500 c.c. of distilled water), and titrate with the approximately N/10 
hydrochloric acid measured from a burette until the color suddenly 
changes from yellow to orange. 

If less than 20 c.c. of the acid are required to neutralize 20 c.c. of 
the N/10 sodium carbonate, the acid is stronger than N/10 and should 
be diluted with sufficient distilled water to reduce its strength to ex- 
actly N/10. 

Example. If 18.9 c.c. of the hydrochloric acid neutralized 20 c.c. 
N/10 sodium carbonate and 945 c.c. of the acid remained for dilution 

945 

^ -X(20.0 18.9) = 55 c.c. of water required to dilute the hydro- 
18.9 

chloric acid to N/10. The strength of the acid adjusted to N/10 should 
be checked by a second titration against the N/10 sodium carbonate. 

B. Tenth-normal Sodium Hydroxide. Dissolve 4.5 grains of dry 
sodium hydroxide C.P. in distilled water free of carbon dioxide and 
dilute to 1,000 c.c. 

Pipette exactly 20 c.c. of this solution into a beaker or flask, add a 
few drops of methyl orange and titrate with the N/10 hydrochloric acid 
as in A above. 

If more than 20 c.c. of N/10 hydrochloric acid are required, the 
sodium hydroxide is stronger than N/10 and should be diluted with dis- 
tilled water to reduce its strength to N/10. 

Example. If 21.1 c.c. of N/10 hydrochloric acid were required to 
neutralize 20 c.c. of the sodium hydroxide and 980 c.c. of the alkali 

remained for dilution^- x (21.1 20.0) = 53.9 c.c. of water required 

to dilute the alkali to exactly N/10. Check the adjusted solution by a 
second titration against N/10 hydrochloric acid. 

97 



98 LABORATORY MANUAL OF 

2. Determination of Acidity. Pipette exactly 10 c.c. of fruit or 
other juice into a flask or beaker, add 50 to 100 c.c. distilled water and 
severs! drops of phenolphthalein (2 grams in 1,000 c.c. of 50 per cent, 
alcohol) and titrate with N/10 sodium hydroxide until a permanent pink 
color is obtained. 

Highly colored samples, such as grape juice, must be diluted to 500 
c.c. or more and more indicator added in order that the color of the 
sample will not mask the end point of the titration. 

In the case of strongly acid products, such as lemon juice or vinegar, 
10 c.c. should be diluted to 100 c.c. with distilled water in a volumetric 
flask. After thorough mixing, withdraw 10 c.c. for determination of acid- 
ity, multiplying the result by 10. 

Factors. One c.c. of N/10 sodium hydroxide will neutralize the fol- 
lowing equivalents of acid: 

Acetic acid 0060 grams Tartaric acid 0075 grams 

Citric acid 0064 grams Lactic acid 0090 grams 

Malic acid 0067 grams Oleic acid 0282 grams 

3. Determination of Alkalinity. The alkalinity of commercial lye 
can be determined by weighing exactly 4.000 grams of a. representative 
sample into a dry beaker. The sample should be weighed as quickly as 
possible to avoid absorption of moisture from the air. Wash the sample 
into a 1,000-c.c. volumetric flask and dilute to the mark with distilled 
water. Mix thoroughly and titrate exactly 20 c.c. with N/10 hydro- 
chloric acid, using phenolphthalein indicator. Since 1 c.c. N/10 hydro- 
chloric acid neutralizes .004 grams of sodium hydroxide, if the above 
directions are followed, each c.c. of acid required is equivalent to 5 per 
cent, sodium hydroxide in the original sample. 

4. Preparation of Standard Silver Nitrate Solution. Weigh ex- 
actly 8.495 grams dry C.P. silver nitrate into a small beaker. Wash into 
a 500-c.c. volumetric flask with distilled water and dilute to 500 c.c. 

If C.P. silver nitrate previously dried three hours at 100C. is em- 
ployed, standardization of the solution is not necessary. The normality 
of the silver nitrate may be verified as follows: Pipette 20 c.c. of N/10 
hydrochloric acid into a beaker or flask; add a few c.c. of chromate 
indicator (5 grams potassium chromate in 100 c.c. distilled water) and 
titrate until the lemon-yellow color changes to a deeper orange color. 
Do not continue till a brick-red color is obtained. Exactly 20 c.c. of the 
silver nitrate solution should be required for this titration. 

5. Determination of Sodium Chloride in Brine. Pipette 10 c.c. of 
the sample into a 100-c.c. volumetric flask. Dilute to the mark with 
distilled water and mix thoroughly. 

Pipette 20 c.c. of the diluted sample into a beaker or flask, add about 



FRUIT AND VEGETABLE PRODUCTS 99 

25 c.c. of distilled water and a few c.c. of chromate indicator, and titrate 
as described in 4. 

One c.c. N/10 silver nitrate is equivalent to .00585 grams of sodium 
chloride. If the above directions are followed each c.c. of N/10 silver 
nitrate equals 0.29 per cent, sodium chloride in the original sample. 

6. Preparation of Standard Iodine and Thiosulphate Solutions: 

A. N/20 Iodine. Weigh exactly 6.346 grams of sublimed iodine 
crystals into a small beaker. Add about 10 to 15 grams of C.P. potas- 
sium iodide and a small amount of distilled water. Stir till the iodine is 
dissolved, wash into a 1,000-c.c. volumetric flask and dilute to the mark 
with distilled water. 

B. N/20 Sodium Thiosulphate. Weigh exactly 12.41 grams of C.P. 
sodium thiosulphate (Na 2 S 2 O 3 . 5H 2 O) into a small beaker; dissolve in 
distilled water; wash into a 1,000-c.c. volumetric flask and dilute to 
the mark. 

C. Standardization. Weigh exactly 2.4516 grams of C.P. potassium 
dichromate into a small beaker. Dissolve and wash into a 1,000-c.c. 
volumetric flask. Dilute to mark with distilled water. Prepare a solu- 
tion containing approximately 10 grams of C.P. potassium iodide in 
100 c.c. of distilled water. 

Place 10 c.c. of this potassium iodide solution and 50 c.c. of distilled 
water in a 200-c.c. Erlenmeyer flask. Add 5 c.c. concentrated hydro- 
chloric acid, and exactly 20 c.c. of the N/20 dichromate solution. Add 
a few drops of starch indicator (prepared by boiling 1 gram of starch 
in 100 c.c. distilled water and preserving with a few drops of chloroform). 
Titrate with the sodium thiosulphate solution until the blue color just 
disappears. 

Since 20 c.c. of the N/20 potassium dichromate solution was used, 
20 c.c. of the thiosulphate solution should be required to react with the 
iodine liberated by the dichromate from the potassium iodide solution. 
The normality of the thiosulphate solution can be determined by dividing 
20 by the c.c. of thiosulphate solution used, and multiplying by .05. 
Example: 21 A c.c. of thiosulphate used. 

on 
Normality = 2 j 4 X. 05 = .0467 N. 

To determine the normality of the iodine solution proceed as follows: 
Pipette 20 c.c. of the iodine solution into a flask or beaker. Add a few 
drops of starch indicator and titrate witli thiosulphate solution till the 
blue color just disappears. The normality of the iodine is then obtained 
from the following formula: 

c.c. thiosulphate usr<l 

' X normality of thiosulphate sol. 



100 LABORATORY MANUAL OF 

Example: Thiosulphate solution used = 21.3 c.c. 

21 3 

Normality of iodine solution = -^- X 0.467 = .04973 N 

zo 

7. Approximate Determination of Total Sulphurous Acid: 

A. Place 50 grams of finely ground dried fruit, or other sample, in 
a 500-c.c. distillation flask. Add about 300 c.c. of distilled water and 
5 c.c. of 20 per cent, phosphoric acid solution. 

B. Connect the flask to a glass condenser and allow the outlet of 
the condenser to dip beneath the surface of 50 c.c. of N/20 iodine solu- 
tion in a 500-c.c. Erlenmeyer flask. 

C. Add not over 1 gram of sodium bicarbonate to the distillation 
flask and quickly insert the rubber stopper connecting to the condenser. 
Distill over about 200 c.c. into the flask containing the iodine solution. 
If all the iodine in the receiving flask is discharged before the distilla- 
tion is complete add more N/20 iodine solution. 

D. Add a few drops of starch indicator to the distillate and titrate 
the excess iodine with N/20 sodium thiosulphate solution until the blue 
color just disappears, leaving a water-white solution. 

E. Report the sulphurous acid content in milligrams per kilogram 
(parts per million) or mgms. per liter of sample. One c.c. N/20 iodine 
equals .0016 gms., or 1.6 mgms. sulphur dioxide. 

8. Preparation of Fehling's Solutions: 

A. Copper Sulphate Solution. Dissolve 34.639 grams of C.P. copper 
sulphate (Cu S0 4 . 5H 2 0) in water and dilute to 500 c.c. 

B. Alkaline Tartrate Solution. Dissolve 173 grams C.P. or U. S. P. 
Rochelle salts (sodium potassium tartrate) and 50 grams stick sodium 
hydroxide in distilled water and dilute to 500 c.c. Mix and allow to 
settle. 

9. Determination of Sugar: 

A. Total Sugar. Preparing the Solution: Weigh exactly an amount 
of sample which when dissolved in distilled water and diluted to 500 
or 1,000 c.c. in a volumetric flask will give a solution containing not more 
than 1 per cent, of sugar. 

Liquid products, such as juices, beverages and syrups, are merely 
diluted without heating. Solid materials, such as fresh or dried fruits, 
must be ground thoroughly before sampling and the weighed sample 
boiled vigorously in water to disintegrate the sample and extract the 
sugar. 

In the case of dried fruits, a representative sample of 1 pound should 
be ground several times through a fine food-chopper with a nut-butter 
attachment, 10 grams placed in a 1,000-c.c. volumetric flask and boiled 
vigorously in 200 to 300 c.c. distilled water for 15 to 20 minutes. 



FRUIT AND VEGETABLE 



101 



Clarifying the Solution: Add to the cooled sugar solution small 
quantities of Home's lead sub-acetate on the tip of a knife-blade, shak- 
ing after each addition until the solution clarifies sharply; that is, the 
solid particles settle rapidly, leaving a practically clear supernatant 
liquid. Fill to the mark with water, mix thoroughly and allow to stand 
overnight. 

Removing Excess Lead: Mix and filter about 50 c.c. through a filter 
paper and add sufficient anhydrous sodium oxalate to precipitate all 
excess lead. Mix and filter again. Test the filtrate with a crystal of 
sodium oxalate to ascertain if free of lead. 

Inverting the Sucrose: Pipette 25 c.c. of the clear filtrate into a 
250-c.c. beaker, add about 5 c.c. concentrated hydrochloric acid and 10 
c.c. water. Heat in a water bath at about 70C. for 10 minutes. Add 
a few drops of indicator and make the solution approximately neutral 
with 20 per cent, sodium hydroxide (about 10 c.c. is required). 

Precipitating the Cuprous Oxide: Add 25 c.c. each of the copper 
sulphate and alkaline tartrate solutions described in 8. Cover the 
beaker with a watch-glass and heat over a Bunsen burner so that boiling 
begins in about 4 minutes and continues exactly 2 minutes. Filter at 
once in a previously dried and weighed Gooch crucible, using gentle 
suction. (The asbestos should be digested previously with acid and 
alkali and washed with distilled water.) Wash all the red cuprous oxide 
into the crucible and wash with hot distilled water until free of soluble 
salts. Dry the crucible in an oven at about 100C. for an hour or 
longer, cool and weigh. 

Calculating the Result: From the weight of cuprous oxide obtained 
find the equivalent weight of invert sugar from Munson and Walker's 
Tables. 1 

Example: 

Milligrams of cuprous oxide obtained = 250.0 
Milligrams of invert sugar equivalent to = 116.4 
Milligrams of original sample represented 

25 c.c. X10 g rams ) =250.0 



\ 1000 c.c.' 
Percentage of total sugar as invert sugar 
116.4 



2500 = 46 - 36 P 01 " ccnt 

B. Invert Sugar (Dextrose and Levulose). In products containing 
only invert sugar, such as grape juice or raisins, the inversion of sucrose 
is omitted. 



321, Methods Analysis of the; Official Agricultural Chemist 1920; or page 599, 
Food Inflection and Analyws.-Lcach. AGRICULTURAL I f 

" 



102 ; 'LABORATORY MANUAL OF 

C. Cane Sugar (Sucrose). In products containing only sucrose, after 
inversion and determination of the sucrose as invert sugar, the percentage 
of invert sugar multiplied by 0.95 gives the percentage of sucrose in the 
sample. 

D. Cane Sugar and Invert Sugar. Where it is desired to determine 
both kinds of sugar present in a sample, determine (a) Invert sugar in 
one aliquot without inversion, (b) Total sugar in another aliquot after 
inversion. The percentage of total sugar as invert sugar minus the per- 
centage of invert sugar obtained without inversion gives the percentage 
of invert sugar resulting from the inversion of the cane sugar, which, 
multiplied by 0.95, gives the percentage of cane sugar (sucrose). 

10. Determination of Moisture: 

A. Samples Not Containing Invert Sugar. Weigh exactly 10 grams 
of finely ground sample into a flat tared dish and dry to constant weight 
in an oven at not over 100C. (212F.). The loss in weight in grams 
multiplied by 10 gives the percentage of moisture. 

B. Samples Containing Invert Sugar, such as Fruits, Honey, etc. 
Proceed as in 10 A, but conduct the drying for 12 hours in a vacuum oven 
at 70C. (158F.) and not over 4 inches mercury pressure. 

11. Detection of Benzoate of Soda. Acidify the sample, such as 
jam, jelly, catsup, cider, etc., with dilute sulphurous acid, after diluting 
with water if necessary. Shake in a separatory funnel with an equal 
volume of chloroform. Draw off the chloroform layer and evaporate it 
to dryness in a porcelain dish. Dissolve the residue in dilute ammonia 
and evaporate to dryness over a water bath. Dissolve the residue in 
a small amount of warm water, filtering if necessary. Add a few drops 
of neutral 0.5 per cent, ferric chloride solution. A brownish precipitate 
indicates the presence of benzoic acid. (A violet color indicates salicylic 
acid.) 

12. Detection of Coal-tar Dye. Boil a strip of white pure-wool 
yarn or cloth for 5 to 15 minutes in a 20- to 100-gram sample of the 
product diluted with an equal volume of water. Remove the cloth and 
rinse thoroughly. Acidify the diluted sample with several drops of con- 
centrated hydrochloric acid and heat again with another piece of wool. 
Remove the cloth and rinse thoroughly. If the cloth takes up any con- 
siderable color in either case, the presence of coal-tar dye is indicated. 

Pure Food and Drug Regulations permit the use of the following 
eight certified colors in food products, if labeled "artificially colored": 
Orange I, Erythrosine, Indigo Carmine, Amaranth, Tartrazine, Napthol 
Yellow S, Ponceau 3 R, Light Green S. F. Yellowish. For the separation 
and identification of these and non-permissible coal-tar dyes, see 
"Methods of Analysis of the Association of Official Agricultural Chem- 
ists, Washington, D. C." 



FRUIT AND VEGETABLE PRODUCTS 



103 



TABLE XIII. TEMPERATURE CORRECTIONS FOR BALLING HYDROMETER. 

To use the table, the apparent sugar percentage (Balling degree) of the syrup is 
determined by hydrometer and the temperature observed. Opposite the indicated 
temperature and in the column below the indicated sugar percentage will be found the 
amount to be added or subtracted from the observed reading. 

Example: 

Observed sugar 50 per cent. 

Observed temperature 115 F. 

Opposite 115 F. and below 50 per cent is found 2.32. This is then added to 50 
per cent, making 52.32, corrected Balling degree. 



Temp. 
Fahr. 


Temp. 
Cent. 


10 


20 


30 


40 60 


75 
Balling 






Corrections to be subtracted from degrees Balling 


32 





.41 


.62 


.82 


.98 


1.22 


1.29 


41 


5 


.37 


.52 


.65 


.75 


.88 


.94 


50 


10 


.29 


.36 


.42 


.49 


.54 


.61 


54 


12.2 


.22 


.26 


.31 


.34 


.40 


.46 


57 


13.9 


.16 


.18 


.21 


.22 


.26 


.32 


61 


16.1 


.08 


.10 


.11 


.12 . 


.14 


.18 


62 


16.7 


.03 


.03 


.04 


.04 


05 


.06 






Corrections to be added to degrees Balling 


64 


17.78 


.03 


.03 


.03 


.03 


.03 .02 


68 


20.00 


.08 


.09 


.10 


.10 


.10 


.06 


72 


22.33 


.29 


.31 


.32 


.33 


.32 


.25 


75 


23.89 


.41 


.44 


.46 


.47 


.46 


.40 


79 


26.11 


.54 


.58 


.61 


.62 


.62 


.55 


82 


27.78 


.68 


.72 


.76 


.78 


.78 


.70 


86 


30.00 


.82 


.92 


.94 


.98 


.88 


.86 


90 


32.23 


.98 


1.03 


1 08 


1.10 


1.10 


.98 


93 


33.89 


1.14 


1.21 


1.24 


1.28 


1.26 


1.17 


97 


36.11 


1.32 


1.38 


1.41 


1.46 


1.42 


1 33 


100 


37.78 


1.49 


1.55 


1.59 


1.64 


1.60 


1.49 


104 


40 00 


1.67 


1.73 


1.79 


1.82 


1.78 


1.65 


108 


42.23 


1.86 


1.93 


1.99 


2.00 


1.96 


1.81 


110 


43.34 


1.96 


2.03 


2.09 


2.10 


2.05 


1.89 


112 


44.45 


2.06 2.13 


2.19 


2 20 


2.14 


1 97 


115 


46.11 


2.27 2.34 


2.39 


2 40 


2.32 


2.35 


117 


47.23 


2.38 2.45 


2.49 


2.50 


2.41 


2.24 


119 


48.34 


2.49 


2.56 


2.59 


2.60 


2.50 


2 23 


121 


49.45 


2 60 


2.67 


2.69 


2.70 


2.60 


2.42 


112 


50.00 


2 71 


2.78 


2.80 


2.80 


2 70 


2.51 


124 


51.11 


2.81 


2.89 


2.90 


2 91 


2.80 


2.60 


126 


52.23 


2.92 


3 00 


3.01 


3.02 


2.90 


2.69 


I2S 


53.34 


3.03 3.11 


3.12 


3.13 


3.00 


2.78 


130 


54.45 


3.14 3 . 22 


3.23 


3 24 


3.10 


2.87 


131 


55.00 


3.26 


3.33 


3.33 


3.29 


3 20 


2 93 


133 


66.11 


3.39 


3.44 


3.44 


3.46 


3.30 


3 05 


135 


57.23 


3.52 


3 55 


3 55 


3 57 


3 40 


3 14 


137 


58 34 


3.64 


3 66 


3.66 


3.68 


3.50 


3.23 


139 


59 45 


3.76 


3.77 


3.77 


3.79 


3.60 


3.32 


140 


60.00 


3.82 


3.88 


3.88 


3.90 


3.70 


3 41 


149 


65.00 


4 53 


4 51 


4.49 


4.48 


4.21 


3.88 


158 


70 00 


5.18 


5.14 


5 10 


5.06 


4 32 


4 35 


167 


75.00 


6.00 


5.84 


5.74 


5 . 66 


5 27 


4.84 


176 


80 00 


6.62 


6.64 


6.38 


6 . 26 


6.82 


5 33 


185 


85.00 


7.44 7.30 


7.10 


6 92 


6.39 


5 85 


194 


90.00 


8 . 26 8 06 


7.85 


7.68 <; r>s 


6 37 


203 


95 00 


9 14 8.89 


8.61 


835 7 ).) 


6 90 


212 


100.00 


10.10 9.72 


9.39 


9 03 


8 . 22 


7 42 



104 



LABORATORY MANUAL OF 



TABLE XIV. RELATION OF SPECIFIC GRAVITY, BATTM^ AND BALLING READINGS OF 

SALT, SUGAR AND SODA LYE SOLUTIONS AT 20C. (68F.) 

(From Cruess, Home and Farm Food Preservation) 



Spec, 
grav. 


Salt 


Sugar 


Soda lye 


Baum6 
degree 


Oz.* per 
gal. 


Balling, 
per cent 
sugar 


Oz.* per 
gal. 


Per cent 


Oz.*per 
gal. 


1.007 


1 


1.3 


1.8 


2.3 


0.5 


0.7 


1.014 


2 


2.6 


3.6 


4.8 


1.2 


1.5 


1.022 


3 


4.0 


5.5 


7.5 


1.8 


2.4 


1.029 


4 


5.3 


7.2 


9.9 


2.5 


3.2 


1.036 


5 


6.7 


9.0 


12.6 


3.1 


4.1 


1.045 


6 


8.1 


10.8 


15.5 


3.7 


5.0 


1.052 


7 


9.6 


12.6 


18.5 


4.5 


6.0 


1.060 


8 


11.1 


14.5 


21.7 


5.2 


7.0 


1.067 


9 


12.7 


16.2 


24.7 


5.8 


8.0 


1.075 


10 


14.2 


18.1 


28.3 


6.6 


9.0 


1.083 


11 


15.8 


19.8 


31.6 


7.3 


10.1 


1.091 


12 


17.5 


21.7 


35.5 


8.1 


11.3 


1.100 


13 


19.1 


23.5 


39.3 


8.8 


12.4 


1.108 


14 


20.8 


25.3 


43.3 


9.5 


13.5 


1.116 


15 


22.6 


27.2 


47.8 


10.3 


14.7 


1.125 


16 


24.4 


29.1 


52.5 


11.1 


15.9 


1.134 


17 


26.2 


30.9 


57.2 


11.9 


17.3 


1.142 


18 


28.1 


32.7 


62.2 


12.7 


18.6 


1.152 


19 


30.0 


34.6 


67.7 


13.5 


19.9 


1.162 


20 


32.0 


36.5 


73.6 


14.3 


21 3 


1.171 


21 


34.0 


38.3 


79.5 


15.1 


22.7 


1.180 


22 


36.1 


40.1 


85.7 


16.0 


24.2 


1.190 


23 


38.2 


42.0 


92.7 


16.9 


25.7 


1.200 


24 


40.4 


43.9 


100.2 


17.8 


27.3 


1.210 


25 


42.7 


45.9 


108.6 


18.7 


29.0 


1.220 


26 


45.0 


47.7 


116.7 


19.6 


30.7 


1.231 


27 


47.3 


49.6 


126.0 


20.6 


32.5 


1.241 


28 


49.8 


51.6 


136.5 


21.5 


34.2 


1.252 


29 


52.3 


53.5 


147.3 


22.5 


36.1 


1.263 


30 


54.9 


55.4 


159.0 


23.5 


38.0 


1.274 


31 


57.5 


57.3 


171.8 


24.5 


39.9 


1.285 


32 


60.2 


59.3 


186.5 


25.5 


41.9 


1.297 


33 


63.0 


61.2 


201.9 


26.6 


44.1 


1.308 


34 


66.0 


63.2 


219.8 


27.6 


46.3 


1.320 


35 


69.0 


65.2 


240.0 


28.8 


48.7 


1.332 


36 


72.0 


67.2 


262.2 


30.0 


51.1 


1.345 


37 


75.2 


69.2 


287.6 


31.2 


53.7 


1.361 


38 


78.4 


71.2 


316.4 


32.4 


56.4 



Ounces of material to be added to one gallon of water. 



FRUIT AND VEGETABLE PRODUCTS 



105 



TABLE XV. MINIMUM DRAINED WEIGHTS FOR CANNED FRUITS AND VEGETABLES 

The following minimum drained weights have been adopted by the United States 
Department of Agriculture, Bureau of Chemistry, in the enforcement of the Pure Food 
and Drugs Act. In each case, the drained or "cut-out" weight is obtained by drain- 
ing the contents of the can on a piece of 1/8-inch mesh screen for 2 minutes. The 
proper filling of canned fruits and vegetables not mentioned in this table is determined 
by visual inspection, no definite weights having been found practicable. 



Material 


Size of can 
No. 


Drained weight (ozs.) 


Remarks 


Beans, Wax and Refugee. 
Beans, green lima 


1 
2 
2 
10 
10 
1 


6 

11H 

12 
61 
65 

8 


Whole beans 
Cut beans 
Whole beans 
Cut beans 


Cherries, unpitted 


2 
10 
1 


13^ 
72 
IQYz 




Cherries, pitted 


2 
2 
2H 
2K 
10 
10 
1 


12 
13 

18 
19 
68 
72 
IVz 


Syrup cut-out above 20 
Syrup cut-out below 20 
Syrup cut-out above 20 
Syrup cut-out below 20 
Syrup cut-out above 20 
Syrup cut-out below 20 
Syrup cut-out above 20 


Corn, Maryland style. . . . 
Peaches, halves or slices . 

Pears 


2 
2 
2H 
2H 
10 
2 
1 
2 
2^ 
10 
1 


12J4 
13H 
18H 
19M 
70 
13H 
10H 
13H 
20 
68 
10-1/2 


Syrup cut-out below 20 
Syrup cut-out above 20 
Syrup cut out above 20 
Syrup cut-out below 20 
Packed in water 

Not pie fruit 


Peas, 


2 

2y 2 

3 
10 
1 


13 
19 
22 
67 
I'M 




Sauerkraut 


2 
10 
2 


IVA 
72 
16 




Spinach 


2H 
3 
10 
2 


23 

27 
80 
13 






2H 
3 
10 


19 

21H 

66 





106 LABORATORY MANUAL 

TABLE XVI. RELATION OF THE BOILING POINT OF WATER TO VACUUM. 



Vacuum in. 
Mercury 


Temp. 
Fahr. 


Vacuum in. 
Mercury 


Temp. 
Fahr. 


Vacuum in. 
Mercury 


Temp. 

Fahr. 


29.0 


79.07 


19.0 


165.42 


9.0 


104.52 


28.0 


101.15 


18.0 


169.14 


8.0 


196.73 


27.0 


115.06 


17.0 


172.63 


7.0 


198.87 


26.0 


125.38 


16.0 


175.93 


6.0 


200.94 


25.0 


133 . 77 


15.0 


179.03 


5.0 


202.92 


24.0 


140.64 


14.0 


181.92 


4.0 


204.85 


23.0 


146.78 


13.0 


184.68 


3.0 


206.71 


22.0 


152.16 


12.0 


187.31 


2.0 


208.52 


21.0 


157.00 


11.0 


189.83 


1.0 


210.28 


20.0 


161.42 


10.0 


192.23 


0.0* 


212.00 



* Zero vacuum is atmospheric pressure or 14.7 Ib. absolute pressure. 

TABLE XVII. BOILING POINT OF WATER AT DIFFERENT ALTITUDES 
ABOVE SEA LEVEL. 





Boiling Point 




Boiling Point 




Boiling Point 


Altitude 




Altitude 




Altitude 




(Feet) 


F. 


c. 


(Feet) 


i. 


a 


(Feet) 


r. 


c. 





212 


100 


4169 


204 


96 


7381 


197 


92 


1025 


210 


99 


5225 


202 


94 


8481 


196 


91 


2063 


208 


98 


6304 


200 


93 


9031 


195 


90 


3115 


206 


97 















TABLE XVIII. SIZE AND CAPACITY OF STANDARD SANITARY CANS USED FOR 
FRUITS AND VEGETABLES. 



Number of Can 


Diameter in Inches 


Height in Inches 


Capacity in Fluid 
Ounces 


1 (Eastern Oyster) . . . 
1 Tall Calif 


2% 
3 


4 

4% 


12 
12 


1 Flat Calif 


4 


2% 


16 


2 


3% 


V/z 


21 


2H 


4 


4% 


31 


3 


4^ 


4K 


35 


10 


6>g 


7 


107 


12 


1 A 


8% 


128 











SELECTED REFERENCES 

Canning 

Bigelow, W. D., Swells and Springers, Bull. 2, National Canners Association. 
Bigelow, W. D., Heat Penetration in Processing Canned Foods, Bull. 16L, National 

Canners Association. 
Bigelow, W. D., Springers and Perforations in Canned Fruits, Circ. 1L, National 

Canners Association. 
Bigelow, W. D., and Cathcart, P. II., Relation of Processing to the Acidity of Canned 

Foods, Bull. 17L, National Canners Association. 

Bitting, A. W., Preliminary Bulletin on Canning, Bull. 1, National Canners Association. 
Bitting, A. W., Methods Followed in the Commercial Canning of Foods, Bull. 1%, 

Bureau of Chemistry, U. S. Dept. of Agr. 

Bitting, A. W., Exhaust and Vacuum, Bull. 8, National Canners Association. 
Bittina, A. W., Processing and Process Devices, Bull. 9, National Canners Association. 
Bitting, A. W., Washing Fruits and Vegetables, Bull. 12, National Canners Association. 
Bitting, A. W., and Bitting, K. G., Bacteriological Examination of Canned Foods. 

Bull. 14, National Canners Association. 

Bitting, K. G., Lye Peeling, Bull. 10, National Canners Association. 
Magoon, C. A., and Culpepper, C. W., A Study of the Factors Affecting Temperature 

Changes in the Container during the Canning of Fruits and Vegetables, Bull. 

956, Bureau of Plant Industry, U. S. Dept. of Agr. 
Magoon, C. A., and Culpepper, C. W:, Relation of Initial Temperature to Pressure, 

Vacuum and Temperature Changes in the Container during Canning Operations, 

Bull. 1022, Bureau of Plant Industry, U. S. Dept. of Agr. 
Zavalla, J. P., The Canning of Fruits and Vegetables, John Wiley and Sons. 
A Complete Course in Canning, The Canning Trade, Baltimore. 
- Home Canning of Fruits and Vegetables, Farmers Bull. 1211, U. S. Dept. 

of Agr. 

Canning Journals 
The Canner, Chicago. 
The Canning Age, New York. 
The Canning Trade, Baltimore. 

Tomato Products 
Bigelow, W. D., and Fitzgerald, F. F., Tomato Pulp, Bull. 3, National Canners 

Association. 
Bigelow, W. D., and Fitzgerald, F. F., Specific Gravity and Solids in Tomato Pulp, 

Bull. 7, National Canners Association. 
Hier, W. G., The Manufacture of Tomato Products, Brock-Hoffner Press Company, 

Denver. 
Howard, B. J., Sanitary Control of Tomato Canning Factories, Bull. 569, IT. S. Dept. 

of Agr. 
Howard, B. J., and Stephensoo, C. II., Microscopical Studies on Tomato Products, 

Hull. 51, IT. S. Dept, of Agr. 

107 



108 LABORATORY MANUAL OF 

Fruit Juices 

Caldwell, J. S., Studies in the Clarification of Unfermented Fruit Juices, Bull. 1025, 
U. S. Dept. of Agr. 

Cruess, W. V., Unfermented Fruit Juices, Circ. 220, University of Calif. Experiment 
Station. 

Dearing, Chas. T., Unfermented Grape Juice, Farmers Bull. 1075, U. S. Dept. of Agr. 

Gore, H. C., Unfermented Apple Juice, Bull. 118, Bureau of Chemistry, U. S. Dept. 
of Agr. 

Gore, H. C., Studies on Fruit Juices, Bull. 241, U. S. Dept. of Agr. 

Hartmann, B. G., and Tolman, L. M., Concord Grape Juice: Manufacture and Chemical 
Composition, Bull. 656, U. S. Dept. of Agr. 

Lewi. , C. I. , and Brown, F. R., Loganberry By-products, Bull. 118, Oregon Experi- 
ment Station. 

Walker, S. S., and McDermott, A. F., The Utilization of Cull Citrus Fruits in Florida, 
Bull. 135, Florida Experiment Station. 

Fruit Syrups 

Bioletti, F. T., and Cruess, W. V., Grapt Syrup, Bull. 303, University of Calif. Experi- 
ment Station. 

Cruess, W. V., Commercial Production of Grape Syrup, Bull. 321, University of Calif. 
Experiment Station. 

Dearing, C. T., Muscadine Grape Syrup, Farmers Bull. 758, U. S. Dept. of Agr. 

Gore, H. C., Apple Syrup and Concentrated Cider, Year Book Separate 639 (1914), 
U. S. Dept. of Agr. 

Hausbrand, E., Evaporating, Condensing and Cooling Apparatus, Scott, Greenwood 
and Son, London. 

Jelly and Marmalade 
Caldwell, J. S., A New Method for the Preparation of Pectin, Bull. 147, Washington 

Agr. Experiment Station. 
Cruess, W. V., Jellies and Marmalades from Citrus Fruits, Circ. 146, University of 

Calif. Experiment Station. 
Goldwaithe, N. E., Principles of Jelly Making, Lesson 114, Food Series, Cornell Agr. 

College Reading Course. 
Goldwaithe, N. E., A Contribution on the Chemistry and Physics of Jelly Making, 

Journal, Industrial and Engineering Chemistry, 1909, pg. 333 
Powell, Ola, Successful Canning and Preserving, J. B. Lippincott Co., Philadelphia, 

Publishers. 

Jam, Preserves, Butter and Paste 

Abell, T. H., Apple Candy, Bull. 179, Utah Experiment Station. 
Close, C. P., Homemade Fruit Butters, Farmers Bull. 900, U. S. Dept. of Agr. 
Dearing, C. T., Muscadine Grape Paste, Farmers Bull. 1033, U. S. Dept. of Agr. 
Pacrettc, J., The Art of Canning and Preserving, Jules H. Dommergue, Jersey City, 

N. J., Publisher. 

Potts, A. T., The Fig in Texas, Bull. 208, Texas Experiment Station. 
Powell, Ola, Successful Canning and Preserving, J. B. Lippincott Co., Philadelphia. 

Dried Fruits and Vegetables 
Beattie, J. H., and Gould, H. P., Commercial Evaporation and Drying of Fruits, 

Farmers Bull. 903, U. S. Dept. of Agr. 
Caldwell, J. S., The Evaporation of Fruits and Vegetables, Bull. 148, Washington 

Experiment Station. 



FRUIT AND VEGETABLE PRODUCTS 109 

Caldwell, J. S., Farm and Home Drying of Fruits and Vegetables, Fanners Bull. 984, 

U. S. Dept. of Agr. 
Cruess, W. V., and Christie, A. W., The Dehydration of Fruits, Bull. 330, University 

of Calif. Experiment Station. 
Cruess, W. V., and Christie, A. W., Some Factors Affecting Dehydrater Efficiency, 

Bull. 387, University of Calif. Experiment Station 
Cruess, W. V., and Christie, A. W., The Evaporation of Grapes, Bull. 322, University 

of Calif. Experiment Station. 

Hausbrand, E., Drying by Means of Air and Steam, Scott, Greenwood and Son, London. 
Parker, W. B., Control of Dried Fruit Insects in California, Bull. 235, Bureau of Ent., 

U. S. Dept. of Agr. 
Prescott, S. C., Relation of Dehydration to Agriculture, Circ. 126, Office of Secretary, 

U. S. Dept. of Agr. 
Tiemann, H. D., The Kiln Drying of Lumber, J. B. Lippincott Co., Philadelphia. 

Fixed and Essential Oils 
Hood, C. S., and Russell, G. A., The Production of Sweet Orange Oil and a New Machine 

for Peeling Citrus Fruits, Department Bull. 399, IT. S. Dept. of Agr. 
Powell, G. H., and Chace, E. M., Italian Lemons and their By-products, Bull. 160, 

Bur. Plant, Ind., U. S. Dept. of Agr. 
Rabak, F., Commercial Utilization of Grape Pomace and Stems from the Grape Juice 

Industry, Department Bull. 952, U. S. Dept. of Agr. 
Rabak, F., The Utilization of Cherry By-products, Department Bull. 350, U. S. Dept. 

of Agr. 
Rabak, F., The Utilization of Waste Tomato Seeds and Skins, Department Bull. 632, 

U. S. Dept. of Agr. 
Rabak, F., Peach, Apricot and Prune Kernels as By-products of the Fruit Industry 

of the United States, Bull. 133, Bur. Plant 'ind., U. S. Dept. of Agr. 
Rabak, F., The Utilization of Waste Raisin Seeds, Bull. 276. Bur. Plant Ind., U. S. 

Dept. of Agr. 

Vinegar and Pickles 
Cruess, W. V., Vinegar from Waste Fruits, Bull. 287, University of Calif. Experiment 

Station. 

Le Fevre, E., Fermented Pickles, Farmers Bull. 1159, IT. S. Dept. of Agr. 
Round, L. A., and Lang, H. L., Preservation of Vegetables by Fermentation and 

Salting, Farmers Bull. 881, U. S. Dept. of Agr. 
Wyant, Z. N., Vinegar, Special Bull. 98, Michigan Experiment Station. 

Methods of Analysis 

Leach, A. E., Food Inspection and Analysis, John Wiley & Sons, N. Y. City. 
Leach, A. E., Methods of Analysis, Association of Official Agricultural Chemists, Wash- 
ington, D. C. 




ITY of CALIFORNIA 

AT 

GELES 
Y 




TX603 

C8 

1922 



Cruess, William Vere 

Laboratory manual of fruit 
and vegetable products. 



UC SOUTHERN REGIONW. LIBRARY FACIL TV 



A 001 445 827 7 






AGRICULTURAL LIBRARY 

UNIVERSITY OF CALIFORNIA 

CITRUS RESEARCH CENTER AND 
AGRILULYU. Al EXPERIMENT STATION 
.. CALIFORNIA